Update libsndfile to 1.0.29pre2+git

This pulls in MANY (over 890) changes compared to our
from our current 1.0.24 version.

lib-src/libsndfile/tests/benchmark-1.0.6pre10-miles

@@ -0,0 +1,39 @@
+Benchmarking libsndfile-1.0.6pre10
+----------------------------------
+Each test takes a little over 5 seconds.
+
+    Raw write PCM_16  :   40092612 samples per sec
+    Raw read  PCM_16  :   42382563 samples per sec
+
+Native endian I/O :
+    Write short   to  PCM_16 :  61.90% of raw write
+    Read  short  from PCM_16 : 100.20% of raw read
+    Write int     to  PCM_24 :  28.69% of raw write
+    Read  int    from PCM_24 :  33.62% of raw read
+    Write int     to  PCM_32 :  31.14% of raw write
+    Read  int    from PCM_32 :  51.04% of raw read
+    Write float   to  PCM_16 :  25.57% of raw write
+    Read  float  from PCM_16 :  28.17% of raw read
+    Write float   to  PCM_24 :  23.59% of raw write
+    Read  float  from PCM_24 :  24.14% of raw read
+    Write float   to  PCM_32 :  18.00% of raw write
+    Read  float  from PCM_32 :  22.59% of raw read
+    Write float   to  FLOAT  :  31.32% of raw write
+    Read  float  from FLOAT  :  51.54% of raw read
+
+Endian swapped I/O :
+    Write short   to  PCM_16 :  42.81% of raw write
+    Read  short  from PCM_16 :  54.58% of raw read
+    Write int     to  PCM_24 :  29.28% of raw write
+    Read  int    from PCM_24 :  33.43% of raw read
+    Write int     to  PCM_32 :  22.21% of raw write
+    Read  int    from PCM_32 :  27.24% of raw read
+    Write float   to  PCM_16 :  25.76% of raw write
+    Read  float  from PCM_16 :  26.84% of raw read
+    Write float   to  PCM_24 :  23.71% of raw write
+    Read  float  from PCM_24 :  24.10% of raw read
+    Write float   to  PCM_32 :  18.47% of raw write
+    Read  float  from PCM_32 :  21.45% of raw read
+    Write float   to  FLOAT  :  22.46% of raw write
+    Read  float  from FLOAT  :  29.72% of raw read
+