Revert "Fix gmake detection for MacOSX"

This reverts commit cf33de27.

This breaks make bug 20033 detection on Linux. If this can not be reliably
detected on OSX, just disable parallelism for GNU make 3.81 on OSX in general,
but leave the detection intact for Linux.

configure.in

@@ -2696,19 +2696,7 @@ if test "$_make_longver" -ge "038200" ; then
 elif test "$_make_longver" -ge "038100" ; then
     AC_MSG_RESULT([$GNUMAKE $_make_version])
     AC_MSG_CHECKING([for GNU make bug 20033])
-    dnl
-    dnl FIXME: mktemp takes different arguments on different platforms:
-    dnl http://stackoverflow.com/questions/2792675/how-portable-is-mktemp1
-    dnl
-    dnl -t means either 'use $TMPDIR' (OK) or 'the following is a template'.
-    dnl and without 'the following is a template', a following template
-    dnl is allowed, so this *may* work on *most* platforms
-    dnl
-    TESTGMAKEBUG20033=`mktemp -d -t MakefileXX`
-    SHA1SUM=sha1sum
-    if test "$_os" = "Darwin"; then
-        SHA1SUM=shasum
-    fi
+    TESTGMAKEBUG20033=`mktemp -d`
     cat > $TESTGMAKEBUG20033/Makefile << EOF
 A := \$(wildcard *.a)
 
@@ -2731,7 +2719,7 @@ define d2
 endef
 
 %.b : %.a
-	\$(eval CHECKSUM := \$(word 1,\$(shell cat \$^ | $SHA1SUM))) \$(if \$(wildcard \$(CACHEDIR)/\$(CHECKSUM)),\
+	\$(eval CHECKSUM := \$(word 1,\$(shell cat \$^ | sha1sum))) \$(if \$(wildcard \$(CACHEDIR)/\$(CHECKSUM)),\
 	\$(call d1,\$(CHECKSUM)),\
 	\$(call d2,\$(CHECKSUM)))
 EOF