mips: vdso: Fix flip/flop vdso building bug

Running "make" on an already compiled kernel tree will rebuild the
vdso library even if this has not been modified.

$ make
  GEN     Makefile
  Using linux as source for kernel
  CALL   linux/scripts/atomic/check-atomics.sh
  CALL   linux/scripts/checksyscalls.sh
<stdin>:1511:2: warning: #warning syscall clone3 not implemented [-Wcpp]
  CHK     include/generated/compile.h
  VDSO    arch/mips/vdso/vdso.so.dbg.raw
  OBJCOPY arch/mips/vdso/vdso.so.raw
  GENVDSO arch/mips/vdso/vdso-image.c
  CC      arch/mips/vdso/vdso-image.o
  AR      arch/mips/vdso/built-in.a
  AR      arch/mips/built-in.a
  CHK     include/generated/autoksyms.h
  GEN     .version
  CHK     include/generated/compile.h
  UPD     include/generated/compile.h
  CC      init/version.o
  AR      init/built-in.a
  LD      vmlinux.o
  MODPOST vmlinux.o
  MODINFO modules.builtin.modinfo
  KSYM    .tmp_kallsyms1.o
  KSYM    .tmp_kallsyms2.o
  LD      vmlinux
  SORTEX  vmlinux
  SYSMAP  System.map
  Building modules, stage 2.
  ITS     arch/mips/boot/vmlinux.gz.its
  OBJCOPY arch/mips/boot/vmlinux.bin
  MODPOST 7 modules
  GZIP    arch/mips/boot/vmlinux.bin.gz
  ITB     arch/mips/boot/vmlinux.gz.itb

The issue is generated by the fact that "if_changed" is called twice
in a single target.

Fix the build bug merging the two commands into a single function.
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Paul Burton <paul.burton@mips.com>

arch/mips/vdso/Makefile

@@ -79,11 +79,14 @@ UBSAN_SANITIZE := n
 # Shared build commands.
 #
 
+quiet_cmd_vdsold_and_vdso_check = LD      $@
+      cmd_vdsold_and_vdso_check = $(cmd_vdsold); $(cmd_vdso_check)
+
 quiet_cmd_vdsold = VDSO    $@
       cmd_vdsold = $(CC) $(c_flags) $(VDSO_LDFLAGS) \
                    -Wl,-T $(filter %.lds,$^) $(filter %.o,$^) -o $@
 
-quiet_cmd_vdsoas_o_S = AS       $@
+quiet_cmd_vdsoas_o_S = AS      $@
       cmd_vdsoas_o_S = $(CC) $(a_flags) -c -o $@ $<
 
 # Strip rule for the raw .so files
@@ -119,8 +122,7 @@ $(obj-vdso): KBUILD_AFLAGS := $(aflags-vdso) $(native-abi)
 $(obj)/vdso.lds: KBUILD_CPPFLAGS := $(ccflags-vdso) $(native-abi)
 
 $(obj)/vdso.so.dbg.raw: $(obj)/vdso.lds $(obj-vdso) FORCE
-	$(call if_changed,vdsold)
-	$(call if_changed,vdso_check)
+	$(call if_changed,vdsold_and_vdso_check)
 
 $(obj)/vdso-image.c: $(obj)/vdso.so.dbg.raw $(obj)/vdso.so.raw \
                      $(obj)/genvdso FORCE
@@ -158,8 +160,7 @@ $(obj)/vdso-o32.lds: $(src)/vdso.lds.S FORCE
 	$(call if_changed_dep,cpp_lds_S)
 
 $(obj)/vdso-o32.so.dbg.raw: $(obj)/vdso-o32.lds $(obj-vdso-o32) FORCE
-	$(call if_changed,vdsold)
-	$(call if_changed,vdso_check)
+	$(call if_changed,vdsold_and_vdso_check)
 
 $(obj)/vdso-o32-image.c: VDSO_NAME := o32
 $(obj)/vdso-o32-image.c: $(obj)/vdso-o32.so.dbg.raw $(obj)/vdso-o32.so.raw \
@@ -199,8 +200,7 @@ $(obj)/vdso-n32.lds: $(src)/vdso.lds.S FORCE
 	$(call if_changed_dep,cpp_lds_S)
 
 $(obj)/vdso-n32.so.dbg.raw: $(obj)/vdso-n32.lds $(obj-vdso-n32) FORCE
-	$(call if_changed,vdsold)
-	$(call if_changed,vdso_check)
+	$(call if_changed,vdsold_and_vdso_check)
 
 $(obj)/vdso-n32-image.c: VDSO_NAME := n32
 $(obj)/vdso-n32-image.c: $(obj)/vdso-n32.so.dbg.raw $(obj)/vdso-n32.so.raw \