LKL build doesn't work with OUTPUT variable other than the source tree

[rodionov]

Running mkdir /tmp/lkl/ && OUTPUT=/tmp/lkl/ make -C tools/lkl all V=1 results in the following error:

...
gcc -Wp,-MMD,scripts/mod/.devicetable-offsets.s.d -nostdinc -I./arch/lkl/include -I./arch/lkl/include/generated -I./include -I./arch/lkl/include/uapi -I./arch/lkl/include/generated/uapi -I./include/uapi -I./include/generated/uapi -include ./include/linux/compiler-version.h -include ./include/linux/kconfig.h -include ./include/linux/compiler_types.h -D__KERNEL__ -fmacro-prefix-map=./= -std=gnu11 -fshort-wchar -funsigned-char -fno-common -fno-PIE -fno-strict-aliasing -fno-builtin -fno-delete-null-pointer-checks -O2 -fno-allow-store-data-races -fno-stack-protector -fno-omit-frame-pointer -fno-optimize-sibling-calls -ftrivial-auto-var-init=zero -fno-stack-clash-protection -fstrict-flex-arrays=3 -fno-strict-overflow -fno-stack-check -fconserve-stack -Wall -Wundef -Werror=implicit-function-declaration -Werror=implicit-int -Werror=return-type -Werror=strict-prototypes -Wno-format-security -Wno-trigraphs -Wno-frame-address -Wno-address-of-packed-member -Wframe-larger-than=1024 -Wno-main -Wno-unused-but-set-variable -Wno-unused-const-variable -Wno-dangling-pointer -Wvla -Wno-pointer-sign -Wcast-function-type -Wno-array-bounds -Wno-alloc-size-larger-than -Wimplicit-fallthrough=5 -Werror=date-time -Werror=incompatible-pointer-types -Werror=designated-init -Wenum-conversion -Wno-unused-but-set-variable -Wno-unused-const-variable -Wno-restrict -Wno-packed-not-aligned -Wno-format-overflow -Wno-format-truncation -Wno-stringop-overflow -Wno-stringop-truncation -Wno-missing-field-initializers -Wno-type-limits -Wno-shift-negative-value -Wno-maybe-uninitialized -Wno-sign-compare -DKBUILD_MODFILE='"scripts/mod/devicetable-offsets"' -DKBUILD_BASENAME='"devicetable_offsets"' -DKBUILD_MODNAME='"devicetable_offsets"' -D__KBUILD_MODNAME=kmod_devicetable_offsets -fverbose-asm -S -o scripts/mod/devicetable-offsets.s scripts/mod/devicetable-offsets.c
In file included from ./arch/lkl/include/asm/bitsperlong.h:4,
                 from ./include/uapi/asm-generic/int-ll64.h:12,
                 from ./include/asm-generic/int-ll64.h:11,
                 from ./include/uapi/asm-generic/types.h:7,
                 from ./arch/lkl/include/generated/uapi/asm/types.h:1,
                 from ./include/uapi/linux/types.h:5,
                 from ./include/linux/types.h:6,
                 from ./include/uapi/linux/mei_uuid.h:12,
                 from ./include/uapi/linux/mei.h:10,
                 from ./include/linux/mod_devicetable.h:12,
                 from scripts/mod/devicetable-offsets.c:3:
./arch/lkl/include/uapi/asm/bitsperlong.h:4:10: fatal error: asm/config.h: No such file or directory
    4 | #include <asm/config.h>
      |          ^~~~~~~~~~~~~~
compilation terminated.
make[2]: *** [scripts/Makefile.build:116: scripts/mod/devicetable-offsets.s] Error 1
make[1]: *** [Makefile:1204: prepare0] Error 2
make: *** [Makefile:91: /tmp/lkl//tools/lkl/lib/lkl.o] Error 2

When OUTPUT variable isn't provided in the make command line, then config.h is generated in $(srctree)/arch/lkl/nclude/generated/uapi/asm/config.h

When OUPUT=/tmp/lkl/ is provided in the make command, then config.h is generated in /tmp/lkl/arch/lkl/include/generated/uapi/asm/config.h

Is there an assumption that config.h should be inside arch/lkl/include/generated/uapi/asm folder? Or we are missing adding path OUTPUT/arch/lkl/include/generated/uapi/asm to the includes?