fixed minor compatibility issues with older compilers

contrib/largeNbDicts/Makefile

@@ -15,7 +15,7 @@ LIBZSTD = $(LIBDIR)/libzstd.a
 CPPFLAGS+= -I$(LIBDIR) -I$(LIBDIR)/common -I$(LIBDIR)/dictBuilder -I$(PROGDIR)
 
 CFLAGS  ?= -O3
-CFLAGS  += -std=c99
+CFLAGS  += -std=gnu99
 DEBUGFLAGS= -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow \
             -Wstrict-aliasing=1 -Wswitch-enum \
             -Wstrict-prototypes -Wundef -Wpointer-arith -Wformat-security \

contrib/largeNbDicts/largeNbDicts.c

@@ -50,6 +50,8 @@
 
 /*---  Macros  ---*/
 #define CONTROL(c)   assert(c)
+#undef MIN
+#define MIN(a,b)   ((a) < (b) ? (a) : (b))
 
 
 /*---  Display Macros  ---*/
@@ -472,9 +474,6 @@ static size_t compressBlocks(size_t* cSizes,   /* optional (can be NULL). If pre
 
 /* ---  Benchmark  --- */
 
-typedef size_t (*BMK_benchFn_t)(const void* src, size_t srcSize, void* dst, size_t dstCapacity, void* customPayload);
-typedef size_t (*BMK_initFn_t)(void* initPayload);
-
 typedef struct {
     ZSTD_DCtx* dctx;
     size_t nbDicts;

programs/util.h

@@ -319,15 +319,17 @@ UTIL_STATIC U32 UTIL_isDirectory(const char* infilename)
 
 UTIL_STATIC U32 UTIL_isLink(const char* infilename)
 {
-#if defined(_WIN32)
-    /* no symlinks on windows */
-    (void)infilename;
-#else
+/* macro guards, as defined in : https://linux.die.net/man/2/lstat */
+#if defined(_BSD_SOURCE) \
+    || (defined(_XOPEN_SOURCE) && (_XOPEN_SOURCE >= 500)) \
+    || (defined(_XOPEN_SOURCE) && defined(_XOPEN_SOURCE_EXTENDED)) \
+    || (defined(_POSIX_C_SOURCE) && (_POSIX_C_SOURCE >= 200112L))
     int r;
     stat_t statbuf;
     r = lstat(infilename, &statbuf);
     if (!r && S_ISLNK(statbuf.st_mode)) return 1;
 #endif
+    (void)infilename;
     return 0;
 }