kbuild: refactor KBUILD_VMLINUX_{OBJS,LIBS} calculation

Do not overwrite core-y or drivers-y. Remove libs-y1 and libs-y2.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

Makefile

@@ -1069,19 +1069,18 @@ vmlinux-alldirs	:= $(sort $(vmlinux-dirs) Documentation \
 build-dirs	:= $(vmlinux-dirs)
 clean-dirs	:= $(vmlinux-alldirs)
 
-core-y		:= $(patsubst %/, %/built-in.a, $(core-y))
-drivers-y	:= $(patsubst %/, %/built-in.a, $(drivers-y))
-libs-y2		:= $(patsubst %/, %/built-in.a, $(filter %/, $(libs-y)))
+# Externally visible symbols (used by link-vmlinux.sh)
+KBUILD_VMLINUX_OBJS := $(head-y) $(patsubst %/,%/built-in.a, $(core-y))
+KBUILD_VMLINUX_OBJS += $(addsuffix built-in.a, $(filter %/, $(libs-y)))
 ifdef CONFIG_MODULES
-libs-y1		:= $(filter-out %/, $(libs-y))
-libs-y2		+= $(patsubst %/, %/lib.a, $(filter %/, $(libs-y)))
+KBUILD_VMLINUX_OBJS += $(patsubst %/, %/lib.a, $(filter %/, $(libs-y)))
+KBUILD_VMLINUX_LIBS := $(filter-out %/, $(libs-y))
 else
-libs-y1		:= $(patsubst %/, %/lib.a, $(libs-y))
+KBUILD_VMLINUX_LIBS := $(patsubst %/,%/lib.a, $(libs-y))
 endif
+KBUILD_VMLINUX_OBJS += $(patsubst %/,%/built-in.a, $(drivers-y))
 
-# Externally visible symbols (used by link-vmlinux.sh)
-export KBUILD_VMLINUX_OBJS := $(head-y) $(core-y) $(libs-y2) $(drivers-y)
-export KBUILD_VMLINUX_LIBS := $(libs-y1)
+export KBUILD_VMLINUX_OBJS KBUILD_VMLINUX_LIBS
 export KBUILD_LDS          := arch/$(SRCARCH)/kernel/vmlinux.lds
 export LDFLAGS_vmlinux
 # used by scripts/Makefile.package