toolchain-clang: Specify -ffile-compilation-dir to omit absolute file paths in debug info

Clang does not remap the src filename in asm files debug info when using
-fdebug-prefix-map but gcc does [1], however, there is an option to help
reproducibility with clang namely ffile-compilation-dir to remove the
source directory from path. use it globally with clang compiler

[1] llvm/llvm-project#56609
Signed-off-by: Khem Raj <[email protected]>

Author: kraj

classes/clang.bbclass

@@ -60,6 +60,8 @@ TUNE_CCARGS:append:toolchain-clang:libc-musl:powerpc = " -mlong-double-64"
 TUNE_CCARGS:append:toolchain-clang = "${@bb.utils.contains("DISTRO_FEATURES", "usrmerge", " --dyld-prefix=/usr", "", d)}"
 
 TUNE_CCARGS:append:toolchain-clang = " -Qunused-arguments"
+# Get rid of absolute paths in .file asm directive
+TUNE_CCARGS:append:toolchain-clang = " -ffile-compilation-dir=."
 
 LDFLAGS:append:toolchain-clang:class-nativesdk:x86-64 = " -Wl,-dynamic-linker,${base_libdir}/ld-linux-x86-64.so.2"
 LDFLAGS:append:toolchain-clang:class-nativesdk:x86 = " -Wl,-dynamic-linker,${base_libdir}/ld-linux.so.2"