Add the common directory back to kernel headers.

There will only be a very small set of non-uapi headers. This is
mostly being done for the scsi headers since the kernel has not
made uapi versions of all of them.

Change-Id: I44904b07ff96de918dc5fcab4e5f117a34cb2a87
diff --git a/core/combo/TARGET_linux-arm.mk b/core/combo/TARGET_linux-arm.mk
index f4f3061..5f0f1d2 100644
--- a/core/combo/TARGET_linux-arm.mk
+++ b/core/combo/TARGET_linux-arm.mk
@@ -166,6 +166,7 @@
 endif
 
 KERNEL_HEADERS_COMMON := $(libc_root)/kernel/uapi
+KERNEL_HEADERS_COMMON += $(libc_root)/kernel/common
 KERNEL_HEADERS_ARCH   := $(libc_root)/kernel/uapi/asm-$(TARGET_$(combo_2nd_arch_prefix)ARCH)
 KERNEL_HEADERS := $(KERNEL_HEADERS_COMMON) $(KERNEL_HEADERS_ARCH)