build: backport a few patches for better Make 4.2+ support

patches/openwrt/0096-scripts-feeds-fix-version-detection-for-Make-4.2.1.patch

+From: Matthias Schiffer <mschiffer@universe-factory.net>
+Date: Wed, 15 Jun 2016 19:31:08 +0200
+Subject: scripts: feeds: fix version detection for Make >= 4.2.1
+
+Signed-off-by: Jo-Philipp Wich <jo@mein.io>
+
+Backport of LEDE df18b3756fef6a28d9194368d3156f0cd85fae19
+
+diff --git a/scripts/feeds b/scripts/feeds
+index f8f29cd..908e56c 100755
+--- a/scripts/feeds
++++ b/scripts/feeds
+@@ -22,7 +22,10 @@ my @mkver = split /\s+/, `$mk -v`, 4;
+ my $valid_mk = 1;
+ $mkver[0] =~ /^GNU/ or $valid_mk = 0;
+ $mkver[1] =~ /^Make/ or $valid_mk = 0;
+-$mkver[2] >= "3.81" or $valid_mk = 0;
++
++my ($mkv1, $mkv2) = split /\./, $mkver[2];
++($mkv1 >= 4 || ($mkv1 == 3 && $mkv2 >= 81)) or $valid_mk = 0;
++
+ $valid_mk or die "Unsupported version of make found: $mk\n";
+ 
+ my @feeds;

patches/openwrt/0097-build-don-t-add-j-for-parallel-builds-with-Make-4.2.patch

+From: Matthias Schiffer <mschiffer@universe-factory.net>
+Date: Wed, 15 Jun 2016 19:31:34 +0200
+Subject: build: don't add -j for parallel builds with Make 4.2+
+
+Make usually passes -j and jobserver arguments as part of MAKEFLAGS. LEDE
+removes MAKEFLAGS to have better control of the build, and re-adds the
+jobserver arguments with -j to the Make commandline where desired.
+
+Make 4.2+ behave differently with these arguments passed on the commandline
+than in MAKEFLAGS: -j will override the jobserver argument and the job
+count will be unlimited.
+
+Moving the flags to MAKEFLAGS will need many packages to be changed and
+tested; therefore, we opt for a less invasive change for now and just
+remove -j for Make 4.2+, as the jobserver argument alone is enough to
+enable parallel builds for these Make versions.
+
+Signed-off-by: Jo-Philipp Wich <jo@mein.io>
+Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
+
+Backport of LEDE 6fb212f2933bbbdf2935124205717c9d0ca72b32
+
+diff --git a/include/host-build.mk b/include/host-build.mk
+index e2b5f2f..44401b8 100644
+--- a/include/host-build.mk
++++ b/include/host-build.mk
+@@ -10,7 +10,7 @@ HOST_INSTALL_DIR ?= $(HOST_BUILD_DIR)/host-install
+ HOST_BUILD_PARALLEL ?=
+ 
+ ifneq ($(CONFIG_PKG_BUILD_USE_JOBSERVER),)
+-  HOST_MAKE_J:=$(if $(MAKE_JOBSERVER),$(MAKE_JOBSERVER) -j)
++  HOST_MAKE_J:=$(if $(MAKE_JOBSERVER),$(MAKE_JOBSERVER) $(if $(filter 3.% 4.0 4.1,$(MAKE_VERSION)),-j))
+ else
+   HOST_MAKE_J:=-j$(CONFIG_PKG_BUILD_JOBS)
+ endif
+diff --git a/include/package.mk b/include/package.mk
+index c69d928..a99cdc6 100644
+--- a/include/package.mk
++++ b/include/package.mk
+@@ -23,7 +23,7 @@ PKG_RELRO_PARTIAL ?= 1
+ PKG_RELRO_FULL ?= 1
+ 
+ ifneq ($(CONFIG_PKG_BUILD_USE_JOBSERVER),)
+-  MAKE_J:=$(if $(MAKE_JOBSERVER),$(MAKE_JOBSERVER) -j)
++  MAKE_J:=$(if $(MAKE_JOBSERVER),$(MAKE_JOBSERVER) $(if $(filter 3.% 4.0 4.1,$(MAKE_VERSION)),-j))
+ else
+   MAKE_J:=-j$(CONFIG_PKG_BUILD_JOBS)
+ endif

patches/openwrt/0098-tools-cmake-fix-parallel-build-with-Make-4.2.patch

+From: Matthias Schiffer <mschiffer@universe-factory.net>
+Date: Wed, 15 Jun 2016 19:31:49 +0200
+Subject: tools/cmake: fix parallel build with Make 4.2+
+
+Avoid using the --parallel argument to the CMake bootstrap, as that doesn't
+allow us to remove the -j argument. Instead, pass the HOST_JOBS arguments
+in MAKEFLAGS.
+
+Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
+
+Backport of LEDE 96db10752483cb07f822686482b44be6c21fbb5f
+
+diff --git a/tools/cmake/Makefile b/tools/cmake/Makefile
+index 08e2b02..6c211de 100644
+--- a/tools/cmake/Makefile
++++ b/tools/cmake/Makefile
+@@ -18,10 +18,11 @@ HOST_CONFIGURE_PARALLEL:=1
+ 
+ include $(INCLUDE_DIR)/host-build.mk
+ 
++HOST_CONFIGURE_CMD := MAKEFLAGS="$(HOST_JOBS)" $(BASH) ./configure
++
+ HOST_CONFIGURE_VARS :=
+ 
+ HOST_CONFIGURE_ARGS := \
+-	--prefix=$(STAGING_DIR_HOST) \
+-	$(if $(MAKE_JOBSERVER),--parallel="$(MAKE_JOBSERVER)")
++	--prefix=$(STAGING_DIR_HOST)
+ 
+ $(eval $(call HostBuild))