build: kernel: build arm kernel modules with -fno-pic

With androidkernel (androideabi) toolchains, -fpic is enabled by default.
At least on my 3.4 arm kernel, this causes an issue with kernel modules:
"Unknown symbol _GLOBAL_OFFSET_TABLE_".

On traditional armeabi toolchains, -fpic is not enabled, resulting in working
kernel modules; let's follow that here.

Change-Id: I3058b5213b34bdde9bb9d744563c7d55cd42d2a5
diff --git a/build/tasks/kernel.mk b/build/tasks/kernel.mk
index c4ddebf..2e81f1b 100644
--- a/build/tasks/kernel.mk
+++ b/build/tasks/kernel.mk
@@ -116,6 +116,11 @@
 # Clear this first to prevent accidental poisoning from env
 MAKE_FLAGS :=
 
+ifeq ($(KERNEL_ARCH),arm)
+  # Avoid "Unknown symbol _GLOBAL_OFFSET_TABLE_" errors
+  MAKE_FLAGS += CFLAGS_MODULE="-fno-pic"
+endif
+
 ifeq ($(KERNEL_ARCH),arm64)
   # Avoid "unsupported RELA relocation: 311" errors (R_AARCH64_ADR_GOT_PAGE)
   MAKE_FLAGS += CFLAGS_MODULE="-fno-pic"