CMake: replace Conan with find_package and add find modules

Also, necessarily coupled with this:
* add CMakeLists.txt for vendored libnyquist
* fix SoundTouch header include paths
* move nyq_reformat_aud_do_response function
* handle portSMF headers installed to portsmf or portSMF

Signed-off-by: Be <be@mixxx.org>

cmake-modules/FindPortSMF.cmake

@@ -0,0 +1,83 @@
+#[=======================================================================[.rst:
+FindPortSMF
+-------
+
+Finds the PortSMF library.
+
+Result Variables
+^^^^^^^^^^^^^^^^
+
+This will define the following variables:
+
+``PortSMF_FOUND``
+  True if the system has the PortSMF library.
+``PortSMF_INCLUDE_DIRS``
+  Include directories needed to use PortSMF.
+``PortSMF_LIBRARIES``
+  Libraries needed to link to PortSMF.
+
+Cache Variables
+^^^^^^^^^^^^^^^
+
+The following cache variables may also be set:
+
+``PortSMF_INCLUDE_DIR``
+  The directory containing ``PortSMF/PortSMF.h``.
+``PortSMF_LIBRARY``
+  The path to the PortSMF library.
+
+#]=======================================================================]
+find_package(PkgConfig QUIET)
+if(PkgConfig_FOUND)
+  pkg_check_modules(PortSMF QUIET portSMF)
+endif()
+
+# Arch installs to portsmf directory
+find_path(PortSMF_INCLUDE_DIR
+  NAMES portsmf/allegro.h
+  PATHS ${PortSMF_INCLUDE_DIRS}
+  DOC "PortSMF include directory"
+)
+if(NOT PortSMF_INCLUDE_DIR)
+  # Debian installs to portSMF directory with capital SMF
+  find_path(PortSMF_INCLUDE_DIR
+    NAMES portSMF/allegro.h
+    PATHS ${PortSMF_INCLUDE_DIRS}
+    DOC "PortSMF include directory"
+  )
+  if(PortSMF_INCLUDE_DIR)
+    set(PORTSMF_CAPITAL 1 CACHE INTERNAL "")
+  endif()
+endif()
+
+mark_as_advanced(PortSMF_INCLUDE_DIR)
+
+# Both Arch and Debian name the library portSMF with capital SMF
+find_library(PortSMF_LIBRARY
+  NAMES portSMF
+  PATHS ${PortSMF_LIBRARY_DIRS}
+  DOC "PortSMF library"
+)
+mark_as_advanced(PortSMF_LIBRARY)
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(
+  PortSMF
+  REQUIRED_VARS
+  PortSMF_LIBRARY
+  PortSMF_INCLUDE_DIR
+)
+
+if(PortSMF_FOUND)
+  set(PortSMF_LIBRARIES ${PortSMF_LIBRARY})
+  set(PortSMF_INCLUDE_DIRS ${PortSMF_INCLUDE_DIR})
+
+  if(NOT TARGET PortSMF::PortSMF)
+    add_library(PortSMF::PortSMF INTERFACE IMPORTED)
+    target_link_libraries(PortSMF::PortSMF INTERFACE "${PortSMF_LIBRARY}")
+    target_include_directories(PortSMF::PortSMF INTERFACE "${PortSMF_INCLUDE_DIR}")
+    if(PORTSMF_CAPITAL)
+      target_compile_definitions(PortSMF::PortSMF INTERFACE PORTSMF_CAPITAL)
+    endif()
+  endif()
+endif()