watchpoint-reuse-slot.exp: Correctly skip unsupported commands.

The test case "watchpoint-reuse-slot.exp" yields a lot of failures on
s390/s390x: all instances of awatch, rwatch, and hbreak are performed
even though they aren't supported on these targets.  This is because
the test case ignores non-support error messages when probing for
support of these commands, like:

    (gdb) rwatch buf.byte[0]
    Target does not support this type of hardware watchpoint.

The patch adds handling for this case in the appropriate
gdb_test_multiple invocations.

gdb/testsuite/
	* gdb.base/watchpoint-reuse-slot.exp: Handle the case that the
	target lacks support for awatch, rwatch, or hbreak.

gdb/testsuite/ChangeLog

@@ -1,3 +1,8 @@
+2014-06-30  Andreas Arnez  <arnez@linux.vnet.ibm.com>
+
+	* gdb.base/watchpoint-reuse-slot.exp: Handle the case that the
+	target lacks support for awatch, rwatch, or hbreak.
+
 2014-06-27  Yao Qi  <yao@codesourcery.com>
 
 	* gdb.multi/dummy-frame-restore.exp: New.

gdb/testsuite/gdb.base/watchpoint-reuse-slot.exp

@@ -103,6 +103,9 @@ foreach cmd {"watch" "awatch" "rwatch"} {
 	-re "You may have requested too many.*$gdb_prompt $" {
 	    unsupported $test
 	}
+	-re "Target does not support.*$gdb_prompt $" {
+	    unsupported $test
+	}
 	-re "$gdb_prompt $" {
 	    pass $test
 	    lappend cmds $cmd
@@ -115,7 +118,10 @@ foreach cmd {"watch" "awatch" "rwatch"} {
 set test "hbreak"
 gdb_test_multiple "hbreak main" $test {
     -re "You may have requested too many.*$gdb_prompt $" {
-	pass $test
+	unsupported $test
+    }
+    -re "No hardware breakpoint support.*$gdb_prompt $" {
+	unsupported $test
     }
     -re "$gdb_prompt $" {
 	pass $test