Merge branch 'backtrace' of github.com:facebook/zstd into backtrace

diff --cc programs/fileio.c
index a2d5af2c431e88e3df574632be46ec49fde36fe1,16bfd530db7a6529dc1a5b59ab89ffc6f30bcd75..1eb9a1e0adcfab35389f330a24baf5fdb343c9ef
--- 1/programs/fileio.c
--- 2/programs/fileio.c
+++ b/programs/fileio.c
@@@ -20,21 -20,7 +20,6 @@@
  #  define _POSIX_SOURCE 1          /* disable %llu warnings with MinGW on Windows */
  #endif
  
- #if defined(__has_feature) && !defined(BACKTRACE_ENABLE) /* Clang compiler */
- #  if (__has_feature(address_sanitizer))
- #    define BACKTRACE_ENABLE 0
- #  endif /* __has_feature(address_sanitizer) */
- #elif defined(__SANITIZE_ADDRESS__) && !defined(BACKTRACE_ENABLE) /* GCC compiler */
- #  define BACKTRACE_ENABLE 0
- #endif
- 
- #if !defined(BACKTRACE_ENABLE)          \
-    && ((defined(__linux__) && defined(__GLIBC__)) \
-        || (defined(__APPLE__) && defined(__MACH__)) )
- #  define BACKTRACE_ENABLE 1
- #endif
- 
--
  /*-*************************************
  *  Includes
  ***************************************/
@@@ -176,8 -159,17 +158,25 @@@ static void clearHandler(void
  /*-*********************************************************
  *  Termination signal trapping (Print debug stack trace)
  ***********************************************************/
++#if defined(__has_feature) && !defined(BACKTRACE_ENABLE) /* Clang compiler */
++#  if (__has_feature(address_sanitizer))
++#    define BACKTRACE_ENABLE 0
++#  endif /* __has_feature(address_sanitizer) */
++#elif defined(__SANITIZE_ADDRESS__) && !defined(BACKTRACE_ENABLE) /* GCC compiler */
++#  define BACKTRACE_ENABLE 0
++#endif
++
+ #if !defined(BACKTRACE_ENABLE)          \
+    && ((defined(__linux__) && defined(__GLIBC__)) \
+        || (defined(__APPLE__) && defined(__MACH__)) )
+ #  define BACKTRACE_ENABLE 1
+ #endif
+ 
+ 
  #if defined(BACKTRACE_ENABLE) && (BACKTRACE_ENABLE>=1)
  
+ #include <execinfo.h>   /* backtrace, backtrace_symbols */
+ 
  #define MAX_STACK_FRAMES    50
  
  static void ABRThandler(int sig) {