Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/scripts/Kconfig.include b/scripts/Kconfig.include
index dad5583..d4adfbe 100644
--- a/scripts/Kconfig.include
+++ b/scripts/Kconfig.include
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0-only
 # Kconfig helper macros
 
 # Convenient variables
@@ -18,13 +19,24 @@
 # Return y if <command> exits with 0, n otherwise
 success = $(if-success,$(1),y,n)
 
+# $(failure,<command>)
+# Return n if <command> exits with 0, y otherwise
+failure = $(if-success,$(1),n,y)
+
 # $(cc-option,<flag>)
 # Return y if the compiler supports <flag>, n otherwise
-cc-option = $(success,$(CC) -Werror $(1) -E -x c /dev/null -o /dev/null)
+cc-option = $(success,$(CC) -Werror $(CLANG_FLAGS) $(1) -E -x c /dev/null -o /dev/null)
 
 # $(ld-option,<flag>)
 # Return y if the linker supports <flag>, n otherwise
 ld-option = $(success,$(LD) -v $(1))
 
+# check if $(CC) and $(LD) exist
+$(error-if,$(failure,command -v $(CC)),compiler '$(CC)' not found)
+$(error-if,$(failure,command -v $(LD)),linker '$(LD)' not found)
+
+# Fail if the linker is gold as it's not capable of linking the kernel proper
+$(error-if,$(success, $(LD) -v | grep -q gold), gold linker '$(LD)' not supported)
+
 # gcc version including patch level
-gcc-version := $(shell,$(srctree)/scripts/gcc-version.sh -p $(CC) | sed 's/^0*//')
+gcc-version := $(shell,$(srctree)/scripts/gcc-version.sh $(CC))