I ran
make test TEST=jdk_collections
and was surprised to see:
make[3]: 12: Command not found
It's trying to actually run a command "12" from my PATH, which is big NONO (dangerous!).

After some poking, I came up with:

--- a/test/Makefile
+++ b/test/Makefile
@@ -48,6 +48,7 @@
 all: jdk_all langtools_all jaxp_all
 
 ifeq ($(TEST_JOBS), 0)
+ $(info EXPR=$(EXPR) JOBS=$(JOBS))
   ifeq ($(shell $(EXPR) $(JOBS) \> 50), 1)
     # JTReg cannot handle more than 50 in concurrency
     JDK_TEST_JOBS=50

which then shows:

EXPR= JOBS=12
make[3]: 12: Command not found

so the problem is that $(EXPR) is an undefined make variable in this particular Makefile.

It's disturbing that such a serious bug can be found in the current Makefiles. I think GNU make offers features to help remove such bugs.