Add parameter to allow enabling/disabling selftests via configure

This is a follow-up of:

  https://sourceware.org/ml/gdb-patches/2018-08/msg00347.html

Instead of going throttle and always enabling our selftests (even in
non-development builds), this patch is a bit more conservative and
introduces a configure option ("--enable-unit-tests") that allows the
user to choose whether she wants unit tests in the build or not.  Note
that the current behaviour is retained: if no option is provided, GDB
will have selftests included in a development build, and will *not*
have selftests included in a non-development build.

The rationale for having this option is still the same: due to the
many racy testcases and random failures we see when running the GDB
testsuite, it is unfortunately not possible to perform a full test
when one is building a downstream package.  As the Fedora GDB
maintainer and one of the Debian GDB uploaders, I feel like this
situation could be improved by, at least, executing our selftests
after the package has been built.

This patch introduces no regressions to our build.

OK?

gdb/ChangeLog:
2018-10-10  Sergio Durigan Junior  <sergiodj@redhat.com>
	    Simon Marchi <simark@simark.ca>

	* README (`configure' options): Add documentation for new
	"--enable-unit-tests" option.
	* acinclude.m4: Include "selftest.m4".
	* configure: Regenerate.
	* configure.ac: Use "GDB_AC_SELFTEST".
	* maint.c (maintenance_selftest): Update message informing
	that selftests have been disabled.
	(maintenance_info_selftests): Likewise.
	* selftest.m4: New file.

gdb/gdbserver/ChangeLog:
2018-10-10  Sergio Durigan Junior  <sergiodj@redhat.com>
	    Simon Marchi <simark@simark.ca>

	* acinclude.m4: Include "../selftest.m4".
	* configure: Regenerate.
	* configure.ac: Use "GDB_AC_SELFTEST".
	* configure.srv: Use "$enable_unittests" instead of
	"$development" when checking whether unit tests have been
	enabled.
	* server.c (captured_main): Update message informing that
	selftests have been disabled.

gdb/testsuite/ChangeLog:
2018-10-10  Sergio Durigan Junior  <sergiodj@redhat.com>

	* gdb.gdb/unittest.exp: Update expected message informing that
	selftests have been disabled.
	* gdb.server/unittest.exp: Likewise.

squash! Add parameter to allow enabling/disabling selftests via configure

3 files changed, 8 insertions, 2 deletions

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index c627578..f907323 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2018-10-10  Sergio Durigan Junior  <sergiodj@redhat.com>
+
+	* gdb.gdb/unittest.exp: Update expected message informing that
+	selftests have been disabled.
+	* gdb.server/unittest.exp: Likewise.
+
 2018-10-09  Tom de Vries  <tdevries@suse.de>
 
 	* lib/gdb.exp (target_supports_scheduler_locking): Replace gdb_start_cmd
diff --git a/gdb/testsuite/gdb.gdb/unittest.exp b/gdb/testsuite/gdb.gdb/unittest.exp
index 1c83585..8e3e9a1 100644
--- a/gdb/testsuite/gdb.gdb/unittest.exp
+++ b/gdb/testsuite/gdb.gdb/unittest.exp
@@ -24,7 +24,7 @@ gdb_test_multiple $test $test {
 	gdb_assert "$num_ran > 0" $test
   }
 
-  -re "Selftests are not available in a non-development build.\r\n$gdb_prompt $" {
+  -re "Selftests have been disabled for this build.\r\n$gdb_prompt $" {
 	unsupported $test
   }
 }
diff --git a/gdb/testsuite/gdb.server/unittest.exp b/gdb/testsuite/gdb.server/unittest.exp
index e947ff2..b0a7c6a 100644
--- a/gdb/testsuite/gdb.server/unittest.exp
+++ b/gdb/testsuite/gdb.server/unittest.exp
@@ -38,7 +38,7 @@ gdb_expect {
 	gdb_assert "$num_ran > 0" $test
     }
 
-    -re "Selftests are not available in a non-development build.\r\n$" {
+    -re "Selftests have been disabled for this build.\r\n$" {
 	unsupported $test
     }