0.3.0: converge relibc to upstream 0.6.0 + Red Bear patches

src/c/stdlib.c

@@ -3,3 +3,11 @@ double strtod(const char *nptr, char **endptr);
 long double strtold(const char *nptr, char **endptr) {
     return (long double)strtod(nptr, endptr);
 }
+
+double relibc_ldtod(const long double* val) {
+    return (double)(*val);
+}
+
+void relibc_dtold(double val, long double* out) {
+    *out = (long double)val;
+}