use restrict everywhere it's required by c99 and/or posix 2008

to deal with the fact that the public headers may be used with pre-c99
compilers, __restrict is used in place of restrict, and defined
appropriately for any supported compiler. we also avoid the form
[restrict] since older versions of gcc rejected it due to a bug in the
original c99 standard, and instead use the form *restrict.

src/stdlib/strtod.c

@@ -16,17 +16,17 @@ static long double strtox(const char *s, char **p, int prec)
 	return y;
 }
 
-float strtof(const char *s, char **p)
+float strtof(const char *restrict s, char **restrict p)
 {
 	return strtox(s, p, 0);
 }
 
-double strtod(const char *s, char **p)
+double strtod(const char *restrict s, char **restrict p)
 {
 	return strtox(s, p, 1);
 }
 
-long double strtold(const char *s, char **p)
+long double strtold(const char *restrict s, char **restrict p)
 {
 	return strtox(s, p, 2);
 }