Fix compilation error with memchr() on VS2005

git-svn-id: https://svn.pjsip.org/repos/pjproject/trunk@790 74dad513-b988-da41-8d7b-12977e46ad98
diff --git a/pjlib/include/pj/string.h b/pjlib/include/pj/string.h
index 78926cb..3eb2ee1 100644
--- a/pjlib/include/pj/string.h
+++ b/pjlib/include/pj/string.h
@@ -468,7 +468,7 @@
  */
 PJ_INLINE(char*) pj_strchr( const pj_str_t *str, int chr)
 {
-    return (char*) memchr(str->ptr, chr, str->slen);
+    return (char*) memchr((char*)str->ptr, chr, str->slen);
 }
 
 /**
@@ -628,7 +628,7 @@
  */
 PJ_INLINE(void*) pj_memchr(const void *buf, int c, pj_size_t size)
 {
-    return memchr(buf, c, size);
+    return (void*)memchr((void*)buf, c, size);
 }