sprinkle compiler attributes over code base

some arm fixes (char is unsigned on arm)

CHANGES

@@ -1,5 +1,7 @@
 0.35:
   add clamp.h (for easy integer overflow prevention)
+  sprinkle compiler attributes over code base
+  some arm fixes (char is unsigned on arm)
 
 0.34:
   be more C99 compliant (Florian Weimer)

compiler.h

@@ -158,6 +158,7 @@
 #define __builtin_constant_p(x) 0
 #endif
 
+#ifndef __dietlibc__
 #if defined(__GNUC__)
 #if __has_attribute(null_terminated_string_arg)
 // Function arguments.
@@ -208,5 +209,6 @@
 
 #endif
 #endif	// !defined(__GNUC__)
+#endif	// !defined(__dietlibc__
 
 #endif

str/str_len.c

@@ -1,3 +1,5 @@
+#include <stddef.h>
+#include "compiler.h"
 #undef __dietlibc__
 #include "str.h"
 

textcode/scan_jsonescape.c

@@ -29,7 +29,7 @@ size_t scan_jsonescape(const char *src,char *dest,size_t *destlen) {
 	  size_t j;
 	  unsigned int cur;
 	  for (cur=j=0; j<4; ++j) {
-	    char x=scan_fromhex(s[i+2+j]);
+	    signed char x=scan_fromhex(s[i+2+j]);
 	    if (x<0) goto abort;	// not hex -> invalid input
 	    cur=(cur<<4) | x;
 	  }