m4: remove equal sign from define directive in ax_valgrind_check.m4

Support for providing equal sign in define directives has been added
only in GNU Make 3.82 [1] and it provides the same semantics (variables
should be recursively expanded) as when it is omitted at all, so let's
remove it in order to preserve compatibility with older GNU Make
versions (like the one used on Travis).

[1] https://git.savannah.gnu.org/cgit/make.git/tree/ChangeLog?h=3.82#n766

* m4/ax_valgrind_check.m4 <define valgrind_tool_rule>: Remove equal
sign.

diff --git a/m4/ax_valgrind_check.m4 b/m4/ax_valgrind_check.m4
index c1ff1a2b688a7db896f6316476cdb9134d15839d..5c14fd922762d445b5db2932c3f30f4fbc973c56 100644 (file)
--- a/m4/ax_valgrind_check.m4
+++ b/m4/ax_valgrind_check.m4
@@ -207,7 +207,7 @@ VALGRIND_LOG_COMPILER = \
        $(valgrind_lt) \
        $(VALGRIND) $(VALGRIND_SUPPRESSIONS) --error-exitcode=1 $(VALGRIND_FLAGS)
 
-define valgrind_tool_rule =
+define valgrind_tool_rule
 check-valgrind-$(1): $$(BUILT_SOURCES)
 ifeq ($$(VALGRIND_ENABLED)-$$(ENABLE_VALGRIND_$(1)),yes-yes)
        $$(valgrind_v_use)$$(MAKE) $$(AM_MAKEFLAGS) check-am \