kernel: Add rust prebuilts to path

Starting with android common kernel 6.6, rust is enabled for arm64 gki.
It currently looks for rust version 1.73.0, so that was selected as the
default. This was only added for the clang compile path as gki requires
clang.

Change-Id: Ie7b57568d74cfb4a28a94c8dc8f4b5c622044317

config/BoardConfigKernel.mk

@@ -31,6 +31,7 @@
 #   TARGET_KERNEL_CLANG_PATH           = Clang prebuilts path, optional
 #
 #   TARGET_KERNEL_LLVM_BINUTILS        = Use LLVM binutils, defaults to true
+#   TARGET_KERNEL_RUST_VERSION         = Rust prebuilts version, optional
 #   TARGET_KERNEL_NO_GCC               = Fully compile the kernel without GCC.
 #                                        Defaults to false
 #   TARGET_KERNEL_VERSION              = Reported kernel version in top level kernel
@@ -96,6 +97,8 @@ else
 endif
 TARGET_KERNEL_CLANG_PATH ?= $(BUILD_TOP)/prebuilts/clang/host/$(HOST_PREBUILT_TAG)/$(KERNEL_CLANG_VERSION)
 
+TARGET_KERNEL_RUST_VERSION ?= 1.73.0c
+
 ifneq ($(USE_CCACHE),)
     ifneq ($(CCACHE_EXEC),)
         # Android 10+ deprecates use of a build ccache. Only system installed ones are now allowed
@@ -188,7 +191,7 @@ else
     KERNEL_MAKE_FLAGS += HOSTCFLAGS="--sysroot=$(BUILD_TOP)/prebuilts/gcc/linux-x86/host/x86_64-linux-glibc2.17-4.8/sysroot -I$(BUILD_TOP)/prebuilts/kernel-build-tools/linux-x86/include"
     KERNEL_MAKE_FLAGS += HOSTLDFLAGS="--sysroot=$(BUILD_TOP)/prebuilts/gcc/linux-x86/host/x86_64-linux-glibc2.17-4.8/sysroot -Wl,-rpath,$(BUILD_TOP)/prebuilts/kernel-build-tools/linux-x86/lib64 -L $(BUILD_TOP)/prebuilts/kernel-build-tools/linux-x86/lib64 -fuse-ld=lld --rtlib=compiler-rt"
 
-    TOOLS_PATH_OVERRIDE += PATH=$(BUILD_TOP)/prebuilts/tools-lineage/$(HOST_PREBUILT_TAG)/bin:$(TARGET_KERNEL_CLANG_PATH)/bin:$$PATH
+    TOOLS_PATH_OVERRIDE += PATH=$(BUILD_TOP)/prebuilts/tools-lineage/$(HOST_PREBUILT_TAG)/bin:$(TARGET_KERNEL_CLANG_PATH)/bin:$(BUILD_TOP)/prebuilts/rust/$(HOST_PREBUILT_TAG)/$(TARGET_KERNEL_RUST_VERSION)/bin:$(BUILD_TOP)/prebuilts/clang-tools/$(HOST_PREBUILT_TAG)/bin:$$PATH
 endif
 
 # Set DTBO image locations so the build system knows to build them