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-1.0.0rc2

@@ -0,0 +1,31 @@
+Benchmarking libsndfile-1.0.0rc2
+--------------------------------
+Each test takes a little over 5 seconds.
+
+    Raw write PCM_16  :   31638069 samples per sec
+    Raw read  PCM_16  :   62788982 samples per sec
+
+Native endian I/O :
+    Write short   to  PCM_16 :  82.37% of raw write
+    Read  short  from PCM_16 :  82.17% of raw read
+    Write int     to  PCM_24 :  30.80% of raw write
+    Read  int    from PCM_24 :  37.95% of raw read
+    Write float   to  PCM_16 :  36.22% of raw write
+    Read  float  from PCM_16 :  23.32% of raw read
+    Write float   to  PCM_24 :  28.41% of raw write
+    Read  float  from PCM_24 :  28.41% of raw read
+    Write float   to  FLOAT  :  28.41% of raw write
+    Read  float  from FLOAT  :  57.50% of raw read
+
+Endian swapped I/O :
+    Write short   to  PCM_16 :  21.73% of raw write
+    Read  short  from PCM_16 :  23.37% of raw read
+    Write int     to  PCM_24 :  31.02% of raw write
+    Read  int    from PCM_24 :  38.24% of raw read
+    Write float   to  PCM_16 :  35.51% of raw write
+    Read  float  from PCM_16 :  19.16% of raw read
+    Write float   to  PCM_24 :  27.37% of raw write
+    Read  float  from PCM_24 :  28.74% of raw read
+    Write float   to  FLOAT  :  15.11% of raw write
+    Read  float  from FLOAT  :  15.60% of raw read
+