Fix a regexp pattern in gdb.base/auto-connect-native-target.exp

When I test gdb head (for 7.8 release) on arm-none-eabi, I find the
following this failure, which are caused by the improper regexp
pattern in the test.

(gdb) help target native^M
Undefined target command: "native".  Try "help target".^M
(gdb) FAIL: gdb.base/auto-connect-native-target.exp: help target native

The space in front of "$gdb_prompt $" looks redundant, and this patch
is to remove it from the regexp pattern.

gdb/testsuite:

2014-06-04  Yao Qi  <yao@codesourcery.com>

	* gdb.base/auto-connect-native-target.exp: Remove redundant
	space from the regexp pattern.

gdb/testsuite/ChangeLog

@@ -1,3 +1,8 @@
+2014-06-04  Yao Qi  <yao@codesourcery.com>
+
+	* gdb.base/auto-connect-native-target.exp: Remove redundant
+	space from the regexp pattern.
+
 2014-06-04  Yao Qi  <yao@codesourcery.com>
 
 	* gdb.base/default.exp: Replace "child" with "native" in

gdb/testsuite/gdb.base/auto-connect-native-target.exp

@@ -27,7 +27,7 @@ set have_native 0
 
 set test "help target native"
 gdb_test_multiple $test $test {
-    -re "Undefined target command.* $gdb_prompt $" {
+    -re "Undefined target command.*$gdb_prompt $" {
 	set have_native 0
     }
     -re "Native process.*$gdb_prompt $" {