kernel: Use pahole from Google prebuilts

This fixes the following warnings:

  13:04:54 Disallowed PATH tool "pahole" used: []string{"pahole", "--version"}
  13:04:54 See https://android.googlesource.com/platform/build/+/master/Changes.md#PATH_Tools for more information.
  "pahole" is not allowed to be used. See https://android.googlesource.com/platform/build/+/master/Changes.md#PATH_Tools for more information.
  /home/bgcngm/android/lineage/kernel/oneplus/sm8550/scripts/pahole-flags.sh: 12: [: Illegal number:
  /home/bgcngm/android/lineage/kernel/oneplus/sm8550/scripts/pahole-flags.sh: 16: [: Illegal number:
  /home/bgcngm/android/lineage/kernel/oneplus/sm8550/scripts/pahole-flags.sh: 20: [: Illegal number:

Change-Id: Ice2a3753301a7b7782037fd35544e2831b258650

build/tasks/kernel.mk

@@ -86,7 +86,6 @@ TARGET_MERGE_DTBS_WILDCARD ?= *
 
 ## Internal variables
 DTC := $(HOST_OUT_EXECUTABLES)/dtc
-PAHOLE := $(HOST_OUT_EXECUTABLES)/pahole
 KERNEL_OUT := $(TARGET_OUT_INTERMEDIATES)/KERNEL_OBJ
 RECOVERY_KERNEL_OUT := $(TARGET_OUT_INTERMEDIATES)/RECOVERY_KERNEL_OBJ
 DTBO_OUT := $(TARGET_OUT_INTERMEDIATES)/DTBO_OBJ
@@ -431,7 +430,7 @@ $(KERNEL_CONFIG): $(KERNEL_OUT) $(ALL_KERNEL_DEFCONFIG_SRCS)
 	@echo "Building Kernel Config"
 	$(call make-kernel-config,$(KERNEL_OUT),$(KERNEL_DEFCONFIG))
 
-$(TARGET_PREBUILT_INT_KERNEL): $(KERNEL_CONFIG) $(DEPMOD) $(DTC) $(PAHOLE)
+$(TARGET_PREBUILT_INT_KERNEL): $(KERNEL_CONFIG) $(DEPMOD) $(DTC)
 	@echo "Building Kernel Image ($(BOARD_KERNEL_IMAGE_NAME))"
 	$(call make-kernel-target,$(BOARD_KERNEL_IMAGE_NAME))
 	$(hide) if grep -q '^CONFIG_OF=y' $(KERNEL_CONFIG); then \
@@ -605,7 +604,7 @@ $(RECOVERY_KERNEL_CONFIG): $(ALL_RECOVERY_KERNEL_DEFCONFIG_SRCS)
 	@echo "Building Recovery Kernel Config"
 	$(call make-kernel-config,$(RECOVERY_KERNEL_OUT),$(RECOVERY_DEFCONFIG))
 
-$(TARGET_PREBUILT_INT_RECOVERY_KERNEL): $(RECOVERY_KERNEL_CONFIG) $(DEPMOD) $(DTC) $(PAHOLE)
+$(TARGET_PREBUILT_INT_RECOVERY_KERNEL): $(RECOVERY_KERNEL_CONFIG) $(DEPMOD) $(DTC)
 	@echo "Building Recovery Kernel Image ($(BOARD_KERNEL_IMAGE_NAME))"
 	$(call make-recovery-kernel-target,$(BOARD_KERNEL_IMAGE_NAME))
 

config/BoardConfigKernel.mk

@@ -219,6 +219,9 @@ KERNEL_MAKE_FLAGS += YACC=$(BUILD_TOP)/prebuilts/build-tools/$(HOST_PREBUILT_TAG
 KERNEL_MAKE_FLAGS += M4=$(BUILD_TOP)/prebuilts/build-tools/$(HOST_PREBUILT_TAG)/bin/m4
 TOOLS_PATH_OVERRIDE += BISON_PKGDATADIR=$(BUILD_TOP)/prebuilts/build-tools/common/bison
 
+# Since Linux 5.10, pahole is required
+KERNEL_MAKE_FLAGS += PAHOLE=$(BUILD_TOP)/prebuilts/kernel-build-tools/linux-x86/bin/pahole
+
 # Set the out dir for the kernel's O= arg
 # This needs to be an absolute path, so only set this if the standard out dir isn't used
 OUT_DIR_PREFIX := $(shell echo $(OUT_DIR) | sed -e 's|/target/.*$$||g')