Use require gdb_skip_xml_test

This changes some tests to use "require gdb_skip_xml_test".

gdb/testsuite/gdb.arch/arc-tdesc-cpu.exp

@@ -13,10 +13,7 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-if {[gdb_skip_xml_test]} {
-    unsupported "arc-tdesc-cpu.exp"
-    return -1
-}
+require !gdb_skip_xml_test
 
 gdb_start
 

gdb/testsuite/gdb.base/info-os.exp

@@ -22,10 +22,7 @@ if {![istarget *-*-linux*]} {
 }
 
 # Support for XML-output is needed to run this test.
-if {[gdb_skip_xml_test]} {
-    unsupported "info-os.exp"
-    return -1
-}
+require !gdb_skip_xml_test
 
 # Compile test program.
 if { [prepare_for_testing "failed to prepare" $testfile $srcfile {debug pthreads}] } {

gdb/testsuite/gdb.mi/list-thread-groups-available.exp

@@ -21,10 +21,7 @@ set MIFLAGS "-i=mi"
 standard_testfile
 
 # Support for XML is needed to run this test.
-if {[gdb_skip_xml_test]} {
-    unsupported "list-thread-groups-available.exp"
-    return -1
-}
+require !gdb_skip_xml_test
 
 if  { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable {debug}] != "" } {
     untested "failed to compile"

gdb/testsuite/gdb.mi/mi-info-os.exp

@@ -23,10 +23,7 @@ if {![istarget *-*-linux*]} {
 }
 
 # Support for XML-output is needed to run this test.
-if {[gdb_skip_xml_test]} {
-    unsupported "mi-info-os.exp"
-    return -1
-}
+require !gdb_skip_xml_test
 
 gdb_exit
 if [mi_gdb_start] {

gdb/testsuite/gdb.xml/maint-xml-dump.exp

@@ -37,10 +37,7 @@
 #
 # 4. Indentation of lines will be preserved so your input file needs
 #    to follow the expected indentation.
-if {[gdb_skip_xml_test]} {
-    unsupported "xml tests not being run"
-    return -1
-}
+require !gdb_skip_xml_test
 
 gdb_start
 

gdb/testsuite/gdb.xml/maint_print_struct.exp

@@ -17,10 +17,7 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-if {[gdb_skip_xml_test]} {
-    unsupported "maint_print_struct.exp"
-    return -1
-}
+require !gdb_skip_xml_test
 
 gdb_start
 

gdb/testsuite/gdb.xml/tdesc-arch.exp

@@ -13,10 +13,7 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-if {[gdb_skip_xml_test]} {
-    unsupported "tdesc-arch.exp"
-    return -1
-}
+require !gdb_skip_xml_test
 
 gdb_start
 

gdb/testsuite/gdb.xml/tdesc-errors.exp

@@ -13,10 +13,7 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-if {[gdb_skip_xml_test]} {
-    unsupported "tdesc-errors.exp"
-    return -1
-}
+require !gdb_skip_xml_test
 
 gdb_start
 

gdb/testsuite/gdb.xml/tdesc-regs.exp

@@ -13,10 +13,7 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-if {[gdb_skip_xml_test]} {
-    unsupported "tdesc-regs.exp"
-    return -1
-}
+require !gdb_skip_xml_test
 
 gdb_start
 

gdb/testsuite/gdb.xml/tdesc-reload.exp

@@ -16,10 +16,7 @@
 # Testing for 'maint print xml-tdesc'.  Check we can print out the
 # current target description and load it back in again.
 
-if {[gdb_skip_xml_test]} {
-    unsupported "xml tests not being run"
-    return -1
-}
+require !gdb_skip_xml_test
 
 standard_testfile
 

gdb/testsuite/gdb.xml/tdesc-xinclude.exp

@@ -13,10 +13,7 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-if {[gdb_skip_xml_test]} {
-    unsupported "tdesc-errors.exp"
-    return -1
-}
+require !gdb_skip_xml_test
 
 gdb_start