[Buildroot] [PATCH] packages: fix and improve support for top-level parallel makefile

[Fabio Porcedda]

To fix packages that fail to build when PARALLEL_JOBS is empty instead
of using an empty PARALLEL_JOBS just avoid to using it in
the MAKE variable.

Check the MAKEFLAGS variable to know automatically if the -j option is
being used, but use the "=" operator instead of the ":=" operator
because it can be checked only in a "recursively expanded variable".
Use "override" because otherwise it's impossible to change the
automatic variable "MAKE".

Signed-off-by: Fabio Porcedda <fabio.porcedda at gmail.com>
---
 Makefile            | 4 ++--
 package/Makefile.in | 3 ++-
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/Makefile b/Makefile
index 8d09725..6c2dcca 100644
--- a/Makefile
+++ b/Makefile
@@ -58,8 +58,8 @@ export HOSTARCH := $(shell uname -m | \
 #
 # Taking into account the above considerations, if you still want to execute
 # this top-level Makefile in parallel comment the ".NOTPARALLEL" line and
-# build using the following command:
-#	make BR2_JLEVEL= -j$((`getconf _NPROCESSORS_ONLN`+1))
+# use the -j<jobs> option when building, e.g:
+#      make -j$((`getconf _NPROCESSORS_ONLN`+1))
 .NOTPARALLEL:
 
 # absolute path
diff --git a/package/Makefile.in b/package/Makefile.in
index fc57427..ed68e35 100644
--- a/package/Makefile.in
+++ b/package/Makefile.in
@@ -18,7 +18,8 @@ PARALLEL_JOBS := $(BR2_JLEVEL)
 endif
 
 MAKE1 := $(HOSTMAKE) -j1
-MAKE := $(HOSTMAKE) $(if $(PARALLEL_JOBS),-j$(PARALLEL_JOBS))
+override MAKE = $(HOSTMAKE) \
+	$(if $(findstring j,$(filter-out --%,$(MAKEFLAGS))),,-j$(PARALLEL_JOBS))
 
 ifeq ($(BR2_TOOLCHAIN_BUILDROOT),y)
 TARGET_VENDOR = $(call qstrip,$(BR2_TOOLCHAIN_BUILDROOT_VENDOR))
-- 
2.3.4