modify parse_size_and_unit() to support percentage

Modify parse_size_and_unit() to support a value followed by a '%'
character. In this case ps is required to be non-NULL to ensure the
caller can detect that case. The returned value will be the integer
value s was pointing to and *ps will point to the '%' character.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

xen/common/lib.c

@@ -476,6 +476,10 @@ unsigned long long parse_size_and_unit(const char *s, const char **ps)
     case 'B': case 'b':
         s1++;
         break;
+    case '%':
+        if ( ps )
+            break;
+        /* fallthrough */
     default:
         ret <<= 10; /* default to kB */
         break;