Fix GDB build failure when $development is false

We don't build GDB selftests bits when $development is false.  However, if
we turn bfd/development.sh:$development to false, common/selftest.c is
compiled which is not expected.  It causes the build failure,

selftest.o: In function `selftests::run_tests(char const*)':
binutils-gdb/gdb/common/selftest.c:97: undefined reference to `selftests::reset()'
collect2: error: ld returned 1 exit status

I fix this issue by putting selftest.o selftest-arch.o into CONFIG_OBS
only when $development is true.  After this is fixed, there are other
build failures in maint.c, this patch fixes them as well.

In the release mode, the output of these commands are:

(gdb) maintenance selftest
Selftests are not available in a non-development build.
(gdb) maintenance selftest foo
Selftests are not available in a non-development build.
(gdb) maintenance info selftests
Selftests are not available in a non-development build.

gdb:

2018-01-08  Yao Qi  <yao.qi@linaro.org>
	    Simon Marchi  <simon.marchi@ericsson.com>

	* Makefile.in (COMMON_SFILES): Remove selftest-arch.c and
	common/selftest.c.
	(COMMON_OBS): Remove selftest.o.
	* configure.ac: Append selftest-arch.c and common/selftest.c to
	CONFIG_SRCS.  Append selftest-arch.o and selftest.o to COMMON_OBS.
	* configure: Re-generated.
	* maint.c (maintenance_selftest): Wrap selftests::run_tests with
	GDB_SELF_TEST.
	(maintenance_info_selftests): Likewise.

gdb/testsuite:

2018-01-08  Simon Marchi  <simon.marchi@ericsson.com>

	* gdb.gdb/unittest.exp: Match output in non-development mode.

1 files changed, 10 insertions, 0 deletions

diff --git a/gdb/maint.c b/gdb/maint.c
index a924f83..70e0011 100644
--- a/gdb/maint.c
+++ b/gdb/maint.c
@@ -939,16 +939,26 @@ show_per_command_cmd (const char *args, int from_tty)
 static void
 maintenance_selftest (const char *args, int from_tty)
 {
+#if GDB_SELF_TEST
   selftests::run_tests (args);
+#else
+  printf_filtered (_("\
+Selftests are not available in a non-development build.\n"));
+#endif
 }
 
 static void
 maintenance_info_selftests (const char *arg, int from_tty)
 {
+#if GDB_SELF_TEST
   printf_filtered ("Registered selftests:\n");
   selftests::for_each_selftest ([] (const std::string &name) {
     printf_filtered (" - %s\n", name.c_str ());
   });
+#else
+  printf_filtered (_("\
+Selftests are not available in a non-development build.\n"));
+#endif
 }