Fix size_t snprintf warning by using PRIuPTR format macro

This is the correct C99 format code for the size_t type when passed
as an argument to the *printf family.  If the platform doesn't
define it, we assume %lu and just cross our fingers that its the
proper setting for a size_t on this system.  On most sane platforms,
"unsigned long" is the underlying type of "size_t".

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

src/common.h

@@ -8,12 +8,17 @@
 #ifdef GIT_HAS_PTHREAD
 # include <pthread.h>
 #endif
+#include <inttypes.h>
 #include <assert.h>
 #include <errno.h>
 #include <stdlib.h>
 #include <unistd.h>
 #include <string.h>
 
+#ifndef PRIuPTR
+# define PRIuPTR "lu"
+#endif
+
 #include "git/common.h"
 
 #define GIT_PATH_MAX 4096

src/odb.c

@@ -88,7 +88,7 @@ int git_obj__loose_object_type(git_otype type)
 static int format_object_header(char *hdr, size_t n, git_obj *obj)
 {
 	const char *type_str = git_obj_type_to_string(obj->type);
-	int len = snprintf(hdr, n, "%s %u", type_str, obj->len);
+	int len = snprintf(hdr, n, "%s %" PRIuPTR, type_str, obj->len);
 
 	assert(len > 0);  /* otherwise snprintf() is broken */
 	assert(len < n);  /* otherwise the caller is broken! */