selftests: use "$(MAKE)" instead of "make"

When doing "make kselftest TARGETS=bpf -j12", bpf progs end up being
compiled sequentially and thus slowly.

The reason is that parent make (tools/testing/selftests/Makefile) does
not share its jobserver with child make
(tools/testing/selftests/bpf/Makefile), therefore the latter runs with
-j1.

Change all instances of "make" to "$(MAKE)", so that the whole make
hierarchy runs using a single jobserver.
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/testing/selftests/Makefile

@@ -126,9 +126,9 @@ endif
 # in the default INSTALL_HDR_PATH usr/include.
 khdr:
 ifeq (1,$(DEFAULT_INSTALL_HDR_PATH))
-	make --no-builtin-rules ARCH=$(ARCH) -C $(top_srcdir) headers_install
+	$(MAKE) --no-builtin-rules ARCH=$(ARCH) -C $(top_srcdir) headers_install
 else
-	make --no-builtin-rules INSTALL_HDR_PATH=$$BUILD/usr \
+	$(MAKE) --no-builtin-rules INSTALL_HDR_PATH=$$BUILD/usr \
 		ARCH=$(ARCH) -C $(top_srcdir) headers_install
 endif
 
@@ -136,35 +136,35 @@ all: khdr
 	@for TARGET in $(TARGETS); do		\
 		BUILD_TARGET=$$BUILD/$$TARGET;	\
 		mkdir $$BUILD_TARGET  -p;	\
-		make OUTPUT=$$BUILD_TARGET -C $$TARGET;\
+		$(MAKE) OUTPUT=$$BUILD_TARGET -C $$TARGET;\
 	done;
 
 run_tests: all
 	@for TARGET in $(TARGETS); do \
 		BUILD_TARGET=$$BUILD/$$TARGET;	\
-		make OUTPUT=$$BUILD_TARGET -C $$TARGET run_tests;\
+		$(MAKE) OUTPUT=$$BUILD_TARGET -C $$TARGET run_tests;\
 	done;
 
 hotplug:
 	@for TARGET in $(TARGETS_HOTPLUG); do \
 		BUILD_TARGET=$$BUILD/$$TARGET;	\
-		make OUTPUT=$$BUILD_TARGET -C $$TARGET;\
+		$(MAKE) OUTPUT=$$BUILD_TARGET -C $$TARGET;\
 	done;
 
 run_hotplug: hotplug
 	@for TARGET in $(TARGETS_HOTPLUG); do \
 		BUILD_TARGET=$$BUILD/$$TARGET;	\
-		make OUTPUT=$$BUILD_TARGET -C $$TARGET run_full_test;\
+		$(MAKE) OUTPUT=$$BUILD_TARGET -C $$TARGET run_full_test;\
 	done;
 
 clean_hotplug:
 	@for TARGET in $(TARGETS_HOTPLUG); do \
 		BUILD_TARGET=$$BUILD/$$TARGET;	\
-		make OUTPUT=$$BUILD_TARGET -C $$TARGET clean;\
+		$(MAKE) OUTPUT=$$BUILD_TARGET -C $$TARGET clean;\
 	done;
 
 run_pstore_crash:
-	make -C pstore run_crash
+	$(MAKE) -C pstore run_crash
 
 # Use $BUILD as the default install root. $BUILD points to the
 # right output location for the following cases:
@@ -184,7 +184,7 @@ ifdef INSTALL_PATH
 	install -m 744 kselftest/prefix.pl $(INSTALL_PATH)/kselftest/
 	@for TARGET in $(TARGETS); do \
 		BUILD_TARGET=$$BUILD/$$TARGET;	\
-		make OUTPUT=$$BUILD_TARGET -C $$TARGET INSTALL_PATH=$(INSTALL_PATH)/$$TARGET install; \
+		$(MAKE) OUTPUT=$$BUILD_TARGET -C $$TARGET INSTALL_PATH=$(INSTALL_PATH)/$$TARGET install; \
 	done;
 
 	@# Ask all targets to emit their test scripts
@@ -203,7 +203,7 @@ ifdef INSTALL_PATH
 		echo "[ -w /dev/kmsg ] && echo \"kselftest: Running tests in $$TARGET\" >> /dev/kmsg" >> $(ALL_SCRIPT); \
 		echo "cd $$TARGET" >> $(ALL_SCRIPT); \
 		echo -n "run_many" >> $(ALL_SCRIPT); \
-		make -s --no-print-directory OUTPUT=$$BUILD_TARGET -C $$TARGET emit_tests >> $(ALL_SCRIPT); \
+		$(MAKE) -s --no-print-directory OUTPUT=$$BUILD_TARGET -C $$TARGET emit_tests >> $(ALL_SCRIPT); \
 		echo "" >> $(ALL_SCRIPT);	    \
 		echo "cd \$$ROOT" >> $(ALL_SCRIPT); \
 	done;
@@ -216,7 +216,7 @@ endif
 clean:
 	@for TARGET in $(TARGETS); do \
 		BUILD_TARGET=$$BUILD/$$TARGET;	\
-		make OUTPUT=$$BUILD_TARGET -C $$TARGET clean;\
+		$(MAKE) OUTPUT=$$BUILD_TARGET -C $$TARGET clean;\
 	done;
 
 .PHONY: khdr all run_tests hotplug run_hotplug clean_hotplug run_pstore_crash install clean