[source] kernel: add compile fix for linux 4.9 on x86

[LEDE Commits]

nbd pushed a commit to source.git, branch master:
https://git.lede-project.org/9c18235b3a6b6c61d4517baedf3d775047885f7d

commit 9c18235b3a6b6c61d4517baedf3d775047885f7d
Author: Felix Fietkau <nbd at nbd.name>
AuthorDate: Mon Feb 6 10:35:19 2017 +0100

    kernel: add compile fix for linux 4.9 on x86
    
    Signed-off-by: Felix Fietkau <nbd at nbd.name>
---
 .../generic/patches-4.9/011-kbuild-export-SUBARCH.patch     | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/target/linux/generic/patches-4.9/011-kbuild-export-SUBARCH.patch b/target/linux/generic/patches-4.9/011-kbuild-export-SUBARCH.patch
new file mode 100644
index 0000000..8a5af88
--- /dev/null
+++ b/target/linux/generic/patches-4.9/011-kbuild-export-SUBARCH.patch
@@ -0,0 +1,13 @@
+--- a/Makefile
++++ b/Makefile
+@@ -414,8 +414,8 @@ KERNELRELEASE = $(shell cat include/conf
+ KERNELVERSION = $(VERSION)$(if $(PATCHLEVEL),.$(PATCHLEVEL)$(if $(SUBLEVEL),.$(SUBLEVEL)))$(EXTRAVERSION)
+ 
+ export VERSION PATCHLEVEL SUBLEVEL KERNELRELEASE KERNELVERSION
+-export ARCH SRCARCH CONFIG_SHELL HOSTCC HOSTCFLAGS CROSS_COMPILE AS LD CC
+-export CPP AR NM STRIP OBJCOPY OBJDUMP
++export ARCH SRCARCH SUBARCH CONFIG_SHELL HOSTCC HOSTCFLAGS CROSS_COMPILE AS LD
++export CC CPP AR NM STRIP OBJCOPY OBJDUMP
+ export MAKE AWK GENKSYMS INSTALLKERNEL PERL PYTHON UTS_MACHINE
+ export HOSTCXX HOSTCXXFLAGS LDFLAGS_MODULE CHECK CHECKFLAGS
+