all uses of mksh_vdirsep should exclude “\builtin” from triggering it

exec.c

@@ -23,7 +23,7 @@
 
 #include "sh.h"
 
-__RCSID("$MirOS: src/bin/mksh/exec.c,v 1.200 2017/10/11 21:04:59 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/exec.c,v 1.201 2017/10/11 21:09:24 tg Exp $");
 
 #ifndef MKSH_DEFAULT_EXECSHELL
 #define MKSH_DEFAULT_EXECSHELL	MKSH_UNIXROOT "/bin/sh"
@@ -1172,11 +1172,7 @@ findcom(const char *name, int flags)
 	char *fpath;
 	union mksh_cchack npath;
 
-	if (mksh_vdirsep(name)
-#ifdef MKSH_DOSPATH
-	    && (strcmp(name, T_builtin) != 0)
-#endif
-	    ) {
+	if (mksh_vdirsep(name)) {
 		insert = 0;
 		/* prevent FPATH search below */
 		flags &= ~FC_FUNC;