xdroid: kernel: Allow to override toolchain prefix used for vDSO32 building

We can override prefix used for normal kernel building with
TARGET_KERNEL_CROSS_COMPILE_PREFIX variable but we can't do the same for
vDSO32. Let's correct this injustice by introducing
TARGET_KERNEL_CROSS_COMPILE_PREFIX_ARM32 variable.

Author: NerdZ3ns

config/BoardConfigKernel.mk

@@ -27,6 +27,8 @@
 #                                          defaults to arm-linux-androidkernel- for arm
 #                                                      aarch64-linux-android- for arm64
 #                                                      x86_64-linux-android- for x86
+#   TARGET_KERNEL_CROSS_COMPILE_PREFIX_ARM32 = Compiler prefix for building vDSO32
+#                                                defaults to arm-linux-androidkernel-
 #
 #   TARGET_KERNEL_CLANG_COMPILE        = Compile kernel with clang, defaults to false
 #
@@ -86,12 +88,26 @@ KERNEL_TOOLCHAIN ?= $(KERNEL_TOOLCHAIN_$(KERNEL_ARCH))
 KERNEL_TOOLCHAIN_PREFIX ?= $(KERNEL_TOOLCHAIN_PREFIX_$(KERNEL_ARCH))
 endif
 
+TARGET_KERNEL_CROSS_COMPILE_PREFIX_ARM32 := $(strip $(TARGET_KERNEL_CROSS_COMPILE_PREFIX_ARM32))
+ifneq ($(TARGET_KERNEL_CROSS_COMPILE_PREFIX_ARM32),)
+KERNEL_TOOLCHAIN_PREFIX_ARM32 ?= $(TARGET_KERNEL_CROSS_COMPILE_PREFIX_ARM32)
+else
+KERNEL_TOOLCHAIN_ARM32 ?= $(KERNEL_TOOLCHAIN_arm)
+KERNEL_TOOLCHAIN_PREFIX_ARM32 ?= $(KERNEL_TOOLCHAIN_PREFIX_arm)
+endif
+
 ifeq ($(KERNEL_TOOLCHAIN),)
 KERNEL_TOOLCHAIN_PATH := $(KERNEL_TOOLCHAIN_PREFIX)
 else
 KERNEL_TOOLCHAIN_PATH := $(KERNEL_TOOLCHAIN)/$(KERNEL_TOOLCHAIN_PREFIX)
 endif
 
+ifeq ($(KERNEL_TOOLCHAIN_ARM32),)
+KERNEL_TOOLCHAIN_PATH_ARM32 := $(KERNEL_TOOLCHAIN_PREFIX_ARM32)
+else
+KERNEL_TOOLCHAIN_PATH_ARM32 := $(KERNEL_TOOLCHAIN_ARM32)/$(KERNEL_TOOLCHAIN_PREFIX_ARM32)
+endif
+
 # We need to add GCC toolchain to the path no matter what
 # for tools like `as`
 KERNEL_TOOLCHAIN_PATH_gcc := $(KERNEL_TOOLCHAIN_$(KERNEL_ARCH))/$(KERNEL_TOOLCHAIN_PREFIX_$(KERNEL_ARCH))
@@ -111,8 +127,8 @@ endif
 
 # Needed for CONFIG_COMPAT_VDSO, safe to set for all arm64 builds
 ifeq ($(KERNEL_ARCH),arm64)
-   KERNEL_CROSS_COMPILE += CROSS_COMPILE_ARM32="$(KERNEL_TOOLCHAIN_arm)/$(KERNEL_TOOLCHAIN_PREFIX_arm)"
-   KERNEL_CROSS_COMPILE += CROSS_COMPILE_COMPAT="$(KERNEL_TOOLCHAIN_arm)/$(KERNEL_TOOLCHAIN_PREFIX_arm)"
+    KERNEL_CROSS_COMPILE += CROSS_COMPILE_ARM32="$(KERNEL_TOOLCHAIN_PATH_ARM32)"
+    KERNEL_CROSS_COMPILE += CROSS_COMPILE_COMPAT="$(KERNEL_TOOLCHAIN_PATH_ARM32)"
 endif
 
 # Clear this first to prevent accidental poisoning from env