Exclude Threadsanitizer instrumentation in exit check

When building libpq there is a check to ensure that we're not
linking against code that calls exit(). This check is using a
heuristic grep with exclusions for known false positives. The
Threadsanitizer library instrumentation for function exits is
named such that it triggers the check, so add an exclusion.

This fix is only applied to the Makefile since the meson build
files don't yet have this check.  Adding the check to meson is
outside the scope of this patch though.

Reported-by: Roman Lozko <lozko.roma@gmail.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/CAEhC_BmNGKgj2wKArH2EAU11BsaHYgLnrRFJGRm5Vs8WJzyiQA@mail.gmail.com

src/interfaces/libpq/Makefile

@@ -105,7 +105,9 @@ backend_src = $(top_srcdir)/src/backend
 # build toolchains insert abort() calls, e.g. to implement assert().)
 # If nm doesn't exist or doesn't work on shlibs, this test will do nothing,
 # which is fine.  The exclusion of __cxa_atexit is necessary on OpenBSD,
-# which seems to insert references to that even in pure C code.
+# which seems to insert references to that even in pure C code. Excluding
+# __tsan_func_exit is necessary when using ThreadSanitizer data race detector
+# which use this function for instrumentation of function exit.
 # Skip the test when profiling, as gcc may insert exit() calls for that.
 # Also skip the test on platforms where libpq infrastructure may be provided
 # by statically-linked libraries, as we can't expect them to honor this
@@ -113,7 +115,7 @@ backend_src = $(top_srcdir)/src/backend
 libpq-refs-stamp: $(shlib)
 ifneq ($(enable_coverage), yes)
 ifeq (,$(filter aix solaris,$(PORTNAME)))
-	@if nm -A -u $< 2>/dev/null | grep -v __cxa_atexit | grep exit; then \
+	@if nm -A -u $< 2>/dev/null | grep -v -e __cxa_atexit -e __tsan_func_exit | grep exit; then \
 		echo 'libpq must not be calling any function which invokes exit'; exit 1; \
 	fi
 endif