* config/mt-vxworks (LDFLAGS): Set to -r.

(CFLAGS_FOR_TARGET): Removed.
* config/vx-gdb.exp: always set prompt; gdb.exp sets it to
  (gdb) and gdb for vxworks uses (vxgdb).

gdb/testsuite/config/mt-vxworks

@@ -1 +1 @@
-CFLAGS_FOR_TARGET = -r
+LDFLAGS = -r

gdb/testsuite/config/vx-gdb.exp

@@ -27,11 +27,7 @@ load_lib gdb.exp
 load_lib vxworks.exp
 
 set shell_prompt "->"
-
-# these need to be initialized only if site.exp doesn't set them
-if ![info exists prompt] then {
-    set prompt "\(vxgdb\)"
-}
+set prompt "\[(\]vxgdb\[)\]"
 
 #
 # gdb_version -- extract and print the version number of gcc