commit ("1e860048c53ee gcc-plugins: simplify GCC plugin-dev capability test")

[Dinh Nguyen]

Hi Masahiro,

With v5.11-rc1 and commit("1e860048c53ee gcc-plugins: simplify GCC 
plugin-dev capability test"), I get this error for my arm 
socfpga_defconfig build. I have been building the kernel the same way 
for many years now. Do you know what I might be doing wrong?

$ make ARCH=arm CROSS_COMPILE=${CROSS_COMPILE}
  SYNC    include/config/auto.conf.cmd
  SYSHDR  arch/arm/include/generated/uapi/asm/unistd-common.h
  SYSHDR  arch/arm/include/generated/uapi/asm/unistd-oabi.h
  SYSHDR  arch/arm/include/generated/uapi/asm/unistd-eabi.h
  REMOVE  arch/arm/include/generated/asm/mm-arch-hooks.h
  HOSTCXX scripts/gcc-plugins/arm_ssp_per_task_plugin.so
In file included from scripts/gcc-plugins/gcc-common.h:103:0,
                 from scripts/gcc-plugins/arm_ssp_per_task_plugin.c:3:
/home/dinguyen/linux_dev/gcc-arm-10.2-2020.11-x86_64-arm-none-linux-gnueabihf/bin/../lib/gcc/arm-none-linux-gnueabihf/10.2.1/plugin/include/builtins.h:23:10: 
fatal error: mpc.h: No such file or directory
#include <mpc.h>
          ^~~~~~~
compilation terminated.
scripts/gcc-plugins/Makefile:47: recipe for target 
'scripts/gcc-plugins/arm_ssp_per_task_plugin.so' failed
make[2]: *** [scripts/gcc-plugins/arm_ssp_per_task_plugin.so] Error 1
scripts/Makefile.build:496: recipe for target 'scripts/gcc-plugins' failed
make[1]: *** [scripts/gcc-plugins] Error 2
Makefile:1190: recipe for target 'scripts' failed
make: *** [scripts] Error 2
make: *** Waiting for unfinished jobs....
  UPD     include/config/kernel.release

Thanks,
Dinh