Integrate PR 12649's race detector directly in the testsuite machinery

This integrates Jan Kratochvil's nice race reproducer from PR
testsuite/12649 into the testsuite infrustructure directly.

With this, one only has to do either 'make check-read1' or 'make check
READ1="1"' to preload the read1.so library into expect.

Currently only enabled for glibc/GNU systems, and if
build==host==target.

gdb/testsuite/ChangeLog:

	* Makefile.in (EXTRA_RULES, CC): New variables, get from
	configure.
	(EXPECT): Handle READ1 being set.
	(all): Depend on EXTRA_RULES.
	(check-read1, expect-read1, read1.so, read1): New rules.
	* README (Testsuite Parameters): Document the READ1 make variable.
	(Race detection): New section.
	* configure: Regenerate.
	* configure.ac: If build==host==target, and running under a
	GNU/glibc system, add read1 to the extra Makefile rules.
	(EXTRA_RULES): AC_SUBST it.
	* lib/read1.c: New file.

gdb/ChangeLog:

	* Makefile.in (check-read1): New rule.

1 files changed, 8 insertions, 0 deletions

diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index b33defe..f251627 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -1098,6 +1098,14 @@ check-perf: force
 	  $(MAKE) $(TARGET_FLAGS_TO_PASS) check-perf; \
 	else true; fi
 
+check-read1: force
+	@if [ -f testsuite/Makefile ]; then \
+	  rootme=`pwd`; export rootme; \
+	  rootsrc=`cd $(srcdir); pwd`; export rootsrc; \
+	  cd testsuite; \
+	  $(MAKE) $(TARGET_FLAGS_TO_PASS) check-read1; \
+	else true; fi
+
 # The idea is to parallelize testing of multilibs, for example:
 #   make -j3 check//sh-hms-sim/{-m1,-m2,-m3,-m3e,-m4}/{,-nofpu}
 # will run 3 concurrent sessions of check, eventually testing all 10