kernel: Add prebuilt m4 to build environment
* android-11 removed M4 from the Allowed list, and provided a
prebuilt binary in prebuilts/build-tools
Change-Id: I83d033ecd35a0e2318210e47309fcc010843347f
diff --git a/config/BoardConfigKernel.mk b/config/BoardConfigKernel.mk
index 3e0ac66..62aa58f 100644
--- a/config/BoardConfigKernel.mk
+++ b/config/BoardConfigKernel.mk
@@ -150,6 +150,7 @@
# Since Linux 4.16, flex and bison are required
KERNEL_MAKE_FLAGS += LEX=$(BUILD_TOP)/prebuilts/build-tools/$(HOST_OS)-x86/bin/flex
KERNEL_MAKE_FLAGS += YACC=$(BUILD_TOP)/prebuilts/build-tools/$(HOST_OS)-x86/bin/bison
+KERNEL_MAKE_FLAGS += M4=$(BUILD_TOP)/prebuilts/build-tools/$(HOST_OS)-x86/bin/m4
TOOLS_PATH_OVERRIDE += BISON_PKGDATADIR=$(BUILD_TOP)/prebuilts/build-tools/common/bison
# Set the out dir for the kernel's O= arg