configure: add check for gcc 4.9.0 up-front

also sets -std=gnu++11 per wxWidgets requirement
closes bug #1506

configure

@@ -896,6 +896,7 @@ infodir
 docdir
 oldincludedir
 includedir
+runstatedir
 localstatedir
 sharedstatedir
 sysconfdir
@@ -1073,6 +1074,7 @@ datadir='${datarootdir}'
 sysconfdir='${prefix}/etc'
 sharedstatedir='${prefix}/com'
 localstatedir='${prefix}/var'
+runstatedir='${localstatedir}/run'
 includedir='${prefix}/include'
 oldincludedir='/usr/include'
 docdir='${datarootdir}/doc/${PACKAGE_TARNAME}'
@@ -1325,6 +1327,15 @@ do
   | -silent | --silent | --silen | --sile | --sil)
     silent=yes ;;
 
+  -runstatedir | --runstatedir | --runstatedi | --runstated \
+  | --runstate | --runstat | --runsta | --runst | --runs \
+  | --run | --ru | --r)
+    ac_prev=runstatedir ;;
+  -runstatedir=* | --runstatedir=* | --runstatedi=* | --runstated=* \
+  | --runstate=* | --runstat=* | --runsta=* | --runst=* | --runs=* \
+  | --run=* | --ru=* | --r=*)
+    runstatedir=$ac_optarg ;;
+
   -sbindir | --sbindir | --sbindi | --sbind | --sbin | --sbi | --sb)
     ac_prev=sbindir ;;
   -sbindir=* | --sbindir=* | --sbindi=* | --sbind=* | --sbin=* \
@@ -1462,7 +1473,7 @@ fi
 for ac_var in	exec_prefix prefix bindir sbindir libexecdir datarootdir \
 		datadir sysconfdir sharedstatedir localstatedir includedir \
 		oldincludedir docdir infodir htmldir dvidir pdfdir psdir \
-		libdir localedir mandir
+		libdir localedir mandir runstatedir
 do
   eval ac_val=\$$ac_var
   # Remove trailing slashes.
@@ -1615,6 +1626,7 @@ Fine tuning of the installation directories:
   --sysconfdir=DIR        read-only single-machine data [PREFIX/etc]
   --sharedstatedir=DIR    modifiable architecture-independent data [PREFIX/com]
   --localstatedir=DIR     modifiable single-machine data [PREFIX/var]
+  --runstatedir=DIR       modifiable per-process data [LOCALSTATEDIR/run]
   --libdir=DIR            object code libraries [EPREFIX/lib]
   --includedir=DIR        C header files [PREFIX/include]
   --oldincludedir=DIR     C header files for non-gcc [/usr/include]
@@ -2887,7 +2899,7 @@ ac_configure="$SHELL $ac_aux_dir/configure"  # Please don't use this var.
 
 
 
-am__api_version='1.14'
+am__api_version='1.15'
 
 # Find a good install program.  We prefer a C program (faster),
 # so one script is as good as another.  But avoid the broken or
@@ -3059,8 +3071,8 @@ test "$program_suffix" != NONE &&
 ac_script='s/[\\$]/&&/g;s/;s,x,x,$//'
 program_transform_name=`$as_echo "$program_transform_name" | sed "$ac_script"`
 
-# expand $ac_aux_dir to an absolute path
-am_aux_dir=`cd $ac_aux_dir && pwd`
+# Expand $ac_aux_dir to an absolute path.
+am_aux_dir=`cd "$ac_aux_dir" && pwd`
 
 if test x"${MISSING+set}" != xset; then
   case $am_aux_dir in
@@ -3079,7 +3091,7 @@ else
 $as_echo "$as_me: WARNING: 'missing' script is too old or missing" >&2;}
 fi
 
-if test x"${install_sh}" != xset; then
+if test x"${install_sh+set}" != xset; then
   case $am_aux_dir in
   *\ * | *\	*)
     install_sh="\${SHELL} '$am_aux_dir/install-sh'" ;;
@@ -3407,8 +3419,8 @@ MAKEINFO=${MAKEINFO-"${am_missing_run}makeinfo"}
 # <http://lists.gnu.org/archive/html/automake/2012-07/msg00014.html>
 mkdir_p='$(MKDIR_P)'
 
-# We need awk for the "check" target.  The system "awk" is bad on
-# some platforms.
+# We need awk for the "check" target (and possibly the TAP driver).  The
+# system "awk" is bad on some platforms.
 # Always define AMTAR for backward compatibility.  Yes, it's still used
 # in the wild :-(  We should find a proper way to deprecate it ...
 AMTAR='$${TAR-tar}'
@@ -3582,6 +3594,7 @@ END
   fi
 fi
 
+
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether to enable maintainer-specific portions of Makefiles" >&5
 $as_echo_n "checking whether to enable maintainer-specific portions of Makefiles... " >&6; }
     # Check whether --enable-maintainer-mode was given.
@@ -19366,6 +19379,56 @@ done
 
 
 
+if test "${ax_cv_c_compiler_vendor}" = "gnu"; then
+
+
+
+
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether we are using gcc 4.9.0 or later" >&5
+$as_echo_n "checking whether we are using gcc 4.9.0 or later... " >&6; }
+if ${ax_cv_gcc_4_9_0+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+
+ax_cv_gcc_4_9_0=no
+if test "$GCC" = "yes"; then
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+#ifdef __GNUC__
+#  if (__GNUC__ > 4) || (__GNUC__ == 4 && __GNUC_MINOR__ > 9) \
+   || (__GNUC__ == 4 && __GNUC_MINOR__ == 9 && __GNUC_PATCHLEVEL__ >= 0)
+     yes;
+#  endif
+#endif
+
+_ACEOF
+if (eval "$ac_cpp conftest.$ac_ext") 2>&5 |
+  $EGREP "yes" >/dev/null 2>&1; then :
+  ax_cv_gcc_4_9_0=yes
+fi
+rm -f conftest*
+
+fi
+
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ax_cv_gcc_4_9_0" >&5
+$as_echo "$ax_cv_gcc_4_9_0" >&6; }
+if test "$ax_cv_gcc_4_9_0" = yes; then
+	gcc_ok=yes
+else
+	gcc_ok=no
+fi
+
+    if test x$gcc_ok = xno; then
+        as_fn_error $? "Audacity requires at least GCC 4.9" "$LINENO" 5
+    fi
+
+    CXXFLAGS="${CXXFLAGS} --std=gnu++11"
+else
+    CXXFLAGS="${CXXFLAGS} --std=c++11"
+fi
+
 
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking CFLAGS for strict prototypes" >&5
 $as_echo_n "checking CFLAGS for strict prototypes... " >&6; }
@@ -19607,7 +19670,6 @@ fi
 
 
 
-
   flag=`echo "$wall_flags" | $SED 'y% .=/+-(){}<>:*,%_______________%'`
 
   { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether the C++ preprocessor accepts the $wall_flags flag" >&5