testsuite: Save dg-do-what-default in mve.exp

mve.exp changed the default dg-do action to "assemble", but then
left it like that for later exp files.  This meant that in a
two-multilib test run, the first arm.exp run would have a default
of "dg-do compile" and the second would have a default of
"dg-do assemble".

2020-04-29  Richard Sandiford  <richard.sandiford@arm.com>

gcc/testsuite/
	* g++.target/arm/mve.exp: Restore the original dg-do-what-default
	before finishing.

gcc/testsuite/ChangeLog

+2020-04-29  Richard Sandiford  <richard.sandiford@arm.com>
+
+	* g++.target/arm/mve.exp: Restore the original dg-do-what-default
+	before finishing.
+
 2020-04-29  Jakub Jelinek  <jakub@redhat.com>
 
 	PR target/94707

gcc/testsuite/g++.target/arm/mve.exp

@@ -35,6 +35,7 @@ global dg_runtest_extra_prunes
 set dg_runtest_extra_prunes ""
 lappend dg_runtest_extra_prunes "warning: switch -m(cpu|arch)=.* conflicts with -m(cpu|arch)=.* switch"
 
+set save-dg-do-what-default ${dg-do-what-default}
 set dg-do-what-default "assemble"
 
 # Initialize `dg'.
@@ -45,5 +46,6 @@ dg-runtest [lsort [glob -nocomplain $srcdir/$subdir/../../gcc.target/arm/mve/int
 	"" $DEFAULT_CXXFLAGS
 
 # All done.
+set dg-do-what-default ${save-dg-do-what-default}
 set dg_runtest_extra_prunes ""
 dg-finish