Add other constants to c and libc

core/c/libc/signal.odin

@@ -10,6 +10,9 @@ when ODIN_OS == "windows" {
 
 sig_atomic_t :: distinct atomic_int
 
+SIG_ATOMIC_MIN :: min(sig_atomic_t)
+SIG_ATOMIC_MAX :: max(sig_atomic_t)
+
 @(default_calling_convention="c")
 foreign libc {
 	signal :: proc(sig: int, func: proc "c" (int)) -> proc "c" (int) ---

core/c/libc/string.odin

@@ -38,7 +38,7 @@ foreign libc {
 	strtok   :: proc(s1: [^]char, s2: cstring) -> [^]char ---
 
 	// 7.24.6 Miscellaneous functions
-	memset   : proc(s: rawptr, c: int, n: size_t) -> rawptr : runtime.memset
 	strerror :: proc(errnum: int) -> [^]char ---
 	strlen   :: proc(s: cstring) -> size_t ---
 }
+memset : proc "c" (s: rawptr, c: int, n: size_t) -> rawptr : runtime.memset