Runtime/math matches; better libc headers

Former-commit-id: bef7db1748

libc/limits.h

@@ -0,0 +1,24 @@
+#ifndef _LIMITS_H_
+#define _LIMITS_H_
+
+#define SCHAR_MAX 0x7f
+#define UCHAR_MAX 0xffU
+
+#if defined(__MWERKS__) && __option(unsigned_char)
+#define CHAR_MIN 0U
+#define CHAR_MAX UCHAR_MAX
+#else
+#define CHAR_MIN SCHAR_MIN
+#define CHAR_MAX SCHAR_MAX
+#endif
+
+#define SHRT_MAX 0x7fff
+#define USHRT_MAX 0xffffU
+
+#define INT_MAX 0x7fffffff
+#define UINT_MAX 0xffffffffU
+
+#define LONG_MAX 0x7fffffffL
+#define ULONG_MAX 0xffffffffUL
+
+#endif