[libc] Allow strtoul() to interpret negative numbers

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/arch/i386/core/runtime.c

 #include <stddef.h>
 #include <stdint.h>
 #include <stdlib.h>
+#include <ctype.h>
 #include <errno.h>
 #include <assert.h>
 #include <ipxe/init.h>

src/core/misc.c

 
 unsigned long strtoul ( const char *p, char **endp, int base ) {
 	unsigned long ret = 0;
+	int negative = 0;
 	unsigned int charval;
 
+	while ( isspace ( *p ) )
+		p++;
+
+	if ( *p == '-' ) {
+		negative = 1;
+		p++;
+	}
+
 	base = strtoul_base ( &p, base );
 
 	while ( 1 ) {
 		p++;
 	}
 
+	if ( negative )
+		ret = -ret;
+
 	if ( endp )
 		*endp = ( char * ) p;
 

src/core/strtoull.c

  */
 unsigned long long strtoull ( const char *p, char **endp, int base ) {
 	unsigned long long ret = 0;
+	int negative = 0;
 	unsigned int charval;
 
+	while ( isspace ( *p ) )
+		p++;
+
+	if ( *p == '-' ) {
+		negative = 1;
+		p++;
+	}
+
 	base = strtoul_base ( &p, base );
 
 	while ( 1 ) {
 		p++;
 	}
 
+	if ( negative )
+		ret = -ret;
+
 	if ( endp )
 		*endp = ( char * ) p;
 

src/include/stdlib.h

 
 #include <stdint.h>
 #include <assert.h>
-#include <ctype.h>
 
 /*****************************************************************************
  *
 {
 	const char *p = *pp;
 
-	while ( isspace ( *p ) )
-		p++;
-
 	if ( base == 0 ) {
 		base = 10;
 		if ( *p == '0' ) {