omni: Use $(HOST_PREBUILT_TAG) where possible

Change-Id: If211d23ce72b3404368cd723cbb9ea801e61802c
diff --git a/build/tasks/cookies.mk b/build/tasks/cookies.mk
index 6c5099a..f2ca0a5 100644
--- a/build/tasks/cookies.mk
+++ b/build/tasks/cookies.mk
@@ -1,7 +1,7 @@
 
 OMNI_TARGET_PACKAGE := $(PRODUCT_OUT)/omni-$(ROM_VERSION).zip
 
-MD5 := prebuilts/build-tools/path/$(HOST_OS)-x86/md5sum
+MD5 := prebuilts/build-tools/path/$(HOST_PREBUILT_TAG)/md5sum
 
 .PHONY: cookies
 cookies: $(INTERNAL_OTA_PACKAGE_TARGET)
diff --git a/build/tasks/kernel.mk b/build/tasks/kernel.mk
index a2c471b..eafaa9f 100644
--- a/build/tasks/kernel.mk
+++ b/build/tasks/kernel.mk
@@ -185,7 +185,7 @@
         # Use the default version of clang if TARGET_KERNEL_CLANG_VERSION hasn't been set by the device config
         KERNEL_CLANG_VERSION := $(LLVM_PREBUILTS_VERSION)
     endif
-    TARGET_KERNEL_CLANG_PATH ?= $(BUILD_TOP)/prebuilts/clang/host/$(HOST_OS)-x86/$(KERNEL_CLANG_VERSION)
+    TARGET_KERNEL_CLANG_PATH ?= $(BUILD_TOP)/prebuilts/clang/host/$(HOST_PREBUILT_TAG)/$(KERNEL_CLANG_VERSION)
     ifeq ($(KERNEL_ARCH),arm64)
         KERNEL_CLANG_TRIPLE ?= CLANG_TRIPLE=aarch64-linux-gnu-
     else ifeq ($(KERNEL_ARCH),arm)
diff --git a/config/BoardConfigKernel.mk b/config/BoardConfigKernel.mk
index 97ceca7..e332f7c 100644
--- a/config/BoardConfigKernel.mk
+++ b/config/BoardConfigKernel.mk
@@ -52,7 +52,7 @@
 KERNEL_ARCH := $(TARGET_KERNEL_ARCH)
 endif
 
-GCC_PREBUILTS := $(BUILD_TOP)/prebuilts/gcc/$(HOST_OS)-x86
+GCC_PREBUILTS := $(BUILD_TOP)/prebuilts/gcc/$(HOST_PREBUILT_TAG)
 # arm64 toolchain
 KERNEL_TOOLCHAIN_arm64 := $(GCC_PREBUILTS)/aarch64/aarch64-linux-android-4.9/bin
 KERNEL_TOOLCHAIN_PREFIX_arm64 := aarch64-linux-android-
@@ -131,7 +131,7 @@
 endif
 
 # Set use the full path to the make command
-KERNEL_MAKE_CMD := $(BUILD_TOP)/prebuilts/build-tools/$(HOST_OS)-x86/bin/make
+KERNEL_MAKE_CMD := $(BUILD_TOP)/prebuilts/build-tools/$(HOST_PREBUILT_TAG)/bin/make
 
 # Set the full path to the gcc command
 ifeq ($(HOST_OS),darwin)
@@ -143,9 +143,9 @@
 KERNEL_MAKE_FLAGS += HOSTCXX=$(KERNEL_HOST_TOOLCHAIN_ROOT)g++
 
 # 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
+KERNEL_MAKE_FLAGS += LEX=$(BUILD_TOP)/prebuilts/build-tools/$(HOST_PREBUILT_TAG)/bin/flex
+KERNEL_MAKE_FLAGS += YACC=$(BUILD_TOP)/prebuilts/build-tools/$(HOST_PREBUILT_TAG)/bin/bison
+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
 
 # Set the out dir for the kernel's O= arg