Issue #11651: Improve Makefile test targets.

- Use -j0 option by default
- Remove duplicate test run in "make test" and "make testuniversal"
- Remove "make memtest" altogether
diff --git a/Makefile.pre.in b/Makefile.pre.in
index c2b1a11..a253f41 100644
--- a/Makefile.pre.in
+++ b/Makefile.pre.in
@@ -747,23 +747,22 @@
 
 ######################################################################
 
-# Test the interpreter (twice, once without .pyc files, once with)
-# In the past, we've had problems where bugs in the marshalling or
-# elsewhere caused bytecode read from .pyc files to behave differently
-# than bytecode generated directly from a .py source file.  Sometimes
-# the bytecode read from a .pyc file had the bug, somtimes the directly
-# generated bytecode.  This is sometimes a very shy bug needing a lot of
-# sample data.
-
-TESTOPTS=	-l $(EXTRATESTOPTS)
+# Run a basic set of regression tests.
+# This excludes some tests that are particularly resource-intensive.
+TESTOPTS=	-j0 $(EXTRATESTOPTS)
 TESTPROG=	$(srcdir)/Lib/test/regrtest.py
 TESTPYTHON=	$(RUNSHARED) ./$(BUILDPYTHON) -Wd -E -bb $(TESTPYTHONOPTS)
 TESTTIMEOUT=	3600
 test:		all platform
-		-find $(srcdir)/Lib -name '*.py[co]' -print | xargs rm -f
-		-$(TESTPYTHON) $(TESTPROG) $(TESTOPTS)
 		$(TESTPYTHON) $(TESTPROG) $(TESTOPTS)
 
+# Run the full test suite twice - once without .pyc files, and once with.
+# In the past, we've had problems where bugs in the marshalling or
+# elsewhere caused bytecode read from .pyc files to behave differently
+# than bytecode generated directly from a .py source file.  Sometimes
+# the bytecode read from a .pyc file had the bug, sometimes the directly
+# generated bytecode.  This is sometimes a very shy bug needing a lot of
+# sample data.
 testall:	all platform
 		-find $(srcdir)/Lib -name '*.py[co]' -print | xargs rm -f
 		$(TESTPYTHON) $(srcdir)/Lib/compileall.py
@@ -771,21 +770,18 @@
 		-$(TESTPYTHON) $(TESTPROG) -uall $(TESTOPTS)
 		$(TESTPYTHON) $(TESTPROG) -uall $(TESTOPTS)
 
-#  Run the unitests for both architectures in a Universal build on OSX
-#  Must be run on an Intel box.
+# Run the test suite for both architectures in a Universal build on OSX.
+# Must be run on an Intel box.
 testuniversal:	all platform
 		if [ `arch` != 'i386' ];then \
 			echo "This can only be used on OSX/i386" ;\
 			exit 1 ;\
 		fi
-		-find $(srcdir)/Lib -name '*.py[co]' -print | xargs rm -f
-		-$(TESTPYTHON) $(TESTPROG) -uall $(TESTOPTS)
 		$(TESTPYTHON) $(TESTPROG) -uall $(TESTOPTS)
 		$(RUNSHARED) /usr/libexec/oah/translate ./$(BUILDPYTHON) -E $(TESTPROG) -uall $(TESTOPTS)
 
-
-# Like testall, but with a single pass only
-# run an optional script to include some information about the build environment
+# Like testall, but with only one pass.
+# Run an optional script to include information about the build environment.
 buildbottest:	all platform
 		-@if which pybuildbot.identify >/dev/null 2>&1; then \
 			pybuildbot.identify "CC='$(CC)'" "CXX='$(CXX)'"; \
@@ -801,12 +797,6 @@
 		-$(TESTPYTHON) $(TESTPROG) $(QUICKTESTOPTS)
 		$(TESTPYTHON) $(TESTPROG) $(QUICKTESTOPTS)
 
-MEMTESTOPTS=    $(QUICKTESTOPTS) -x test_dl test___all__ test_fork1 \
-		test_longexp
-memtest:	all platform
-		-rm -f $(srcdir)/Lib/test/*.py[co]
-		-$(TESTPYTHON) $(TESTPROG) $(MEMTESTOPTS)
-		$(TESTPYTHON) $(TESTPROG) $(MEMTESTOPTS)
 
 install: altinstall bininstall
 
@@ -1381,7 +1371,7 @@
 Python/thread.o: @THREADHEADERS@
 
 # Declare targets that aren't real files
-.PHONY: all build_all sharedmods oldsharedmods test quicktest memtest
+.PHONY: all build_all sharedmods oldsharedmods test quicktest
 .PHONY: install altinstall oldsharedinstall bininstall altbininstall
 .PHONY: maninstall libinstall inclinstall libainstall sharedinstall
 .PHONY: frameworkinstall frameworkinstallframework frameworkinstallstructure