Revert "make isspace static" - prototype for isspace() is defined by C99, so can't be static

This reverts commit ed06bd8a89.

src/core/misc.c

 	return 0;
 }
 
-static int isspace ( int c ) {
+int isspace ( int c ) {
 	switch ( c ) {
 	case ' ':
 	case '\f':