Stop using nowarnings in gdb/testsuite/gdb.multi/

Several of the gdb.multi tests use the "nowarnings" option to suppress
warnings.  The warnings in question all come from missing headers,
like e.g.:

 src/gdb/testsuite/gdb.multi/multi-arch-exec.c:28:3: warning: incompatible implicit declaration of built-in function 'exit' [enabled by default]
    exit (1);
    ^

There's no point in trying to avoid to include standard headers.  In
gdb.base/hangout.c's case, it's even dangerous, as that file calls
printf.  In order to compile a call to a variatic function correctly,
a declaration must be visible.

gdb/testsuite/ChangeLog:
2015-12-10  Pedro Alves  <palves@redhat.com>

	* gdb.multi/base.exp: Don't use nowarnings.
	* gdb.multi/bkpt-multi-exec.exp: Don't use nowarnings.
	* gdb.multi/hangout.c: Include stdio.h.
	* gdb.multi/hello.c: Include stdlib.h.
	* gdb.multi/multi-arch-exec.c: Include stdlib.h.
	* gdb.multi/multi-arch-exec.exp: Don't use nowarnings.
	* gdb.multi/multi-arch.exp: Don't use nowarnings.

gdb/testsuite/ChangeLog

@@ -1,3 +1,13 @@
+2015-12-10  Pedro Alves  <palves@redhat.com>
+
+	* gdb.multi/base.exp: Don't use nowarnings.
+	* gdb.multi/bkpt-multi-exec.exp: Don't use nowarnings.
+	* gdb.multi/hangout.c: Include stdio.h.
+	* gdb.multi/hello.c: Include stdlib.h.
+	* gdb.multi/multi-arch-exec.c: Include stdlib.h.
+	* gdb.multi/multi-arch-exec.exp: Don't use nowarnings.
+	* gdb.multi/multi-arch.exp: Don't use nowarnings.
+
 2015-12-10  Andrew Burgess  <andrew.burgess@embecosm.com>
 
 	* gdb.dwarf2/dw2-ranges-base.c: New file.

gdb/testsuite/gdb.multi/base.exp

@@ -30,15 +30,15 @@ set exec3 "goodbye"
 set srcfile3 ${exec3}.c
 set binfile3 [standard_output_file ${exec3}]
 
-if { [build_executable ${testfile}.exp ${exec1} "${srcfile1}" {debug nowarnings}] == -1 } {
+if { [build_executable ${testfile}.exp ${exec1} "${srcfile1}" {debug}] == -1 } {
     return -1
 }
 
-if { [build_executable ${testfile}.exp ${exec2} "${srcfile2}" {debug nowarnings}] == -1} {
+if { [build_executable ${testfile}.exp ${exec2} "${srcfile2}" {debug}] == -1} {
     return -1
 }
 
-if { [build_executable ${testfile}.exp ${exec3} "${srcfile3}" {debug nowarnings}] == -1 } {
+if { [build_executable ${testfile}.exp ${exec3} "${srcfile3}" {debug}] == -1 } {
     return -1
 }
 

gdb/testsuite/gdb.multi/bkpt-multi-exec.exp

@@ -33,7 +33,7 @@ set exec2 "crashme"
 set srcfile2 ${exec2}.c
 set binfile2 [standard_output_file ${exec2}]
 
-set compile_options {debug nowarnings}
+set compile_options {debug}
 set dirname [relative_filename [pwd] [file dirname $binfile1]]
 lappend compile_options "additional_flags=-DBASEDIR=\"$dirname\""
 

gdb/testsuite/gdb.multi/hangout.c

@@ -15,6 +15,8 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
+#include <stdio.h>
+
 main(int argc, char *argv[])
 {
   int i;

gdb/testsuite/gdb.multi/hello.c

@@ -15,6 +15,8 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
+#include <stdlib.h>
+
 short hglob = 1;
 
 short glob = 92;

gdb/testsuite/gdb.multi/multi-arch-exec.c

@@ -15,6 +15,7 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
+#include <stdlib.h>
 #include <stdio.h>
 #include <unistd.h>
 

gdb/testsuite/gdb.multi/multi-arch-exec.exp

@@ -54,13 +54,13 @@ if [istarget "s390*-*-*"] {
 
 set dirname [relative_filename [pwd] [file dirname $binfile2]]
 if { [prepare_for_testing ${testfile}.exp ${exec1} "${srcfile1}" \
-	  [list debug nowarnings \
+	  [list debug \
 	       additional_flags=${march1} \
 	       additional_flags=-DBASEDIR=\"$dirname\"]] } {
     return -1
 }
 
-set options [list debug nowarnings]
+set options [list debug]
 
 if { [istarget "aarch64*-*-*"] } {
     if {[info exists ARM_CC_FOR_TARGET]} {

gdb/testsuite/gdb.multi/multi-arch.exp

@@ -53,11 +53,11 @@ if [istarget "s390*-*-*"] {
 }
 
 if { [prepare_for_testing ${testfile}.exp ${exec1} "${srcfile1}" \
-	  [list debug nowarnings additional_flags=${march1}]] } {
+	  [list debug additional_flags=${march1}]] } {
     return -1
 }
 
-set options [list debug nowarnings]
+set options [list debug]
 
 if [istarget "aarch64*-*-*"] {
     if {[info exists ARM_CC_FOR_TARGET]} {