While building for ARM with our custom clang toolchain, we get the following strange error. This does not happen for AMD64 boards.
And it seems to happen at the end of the build. 
Only happens within the chroot (ebuild build). 
host compiler is clang. 


chromeos-chrome-54.0.2800.2_rc-r1: [29322/29378] STAMP nacl_bootstrap_arm/obj/native_client/src/trusted/service_runtime/linux/nacl_bootstrap_raw.inputdeps.stamp
chromeos-chrome-54.0.2800.2_rc-r1: [29322/29378] ACTION //native_client/src/trusted/service_runtime/linux:nacl_bootstrap_raw(//native_client/src/trusted/service_runtime/linux/toolchain:nacl_bootstrap_arm)
chromeos-chrome-54.0.2800.2_rc-r1: [29323/29378] ACTION //native_client/src/trusted/service_runtime/linux:nacl_bootstrap_raw(//native_client/src/trusted/service_runtime/linux/toolchain:nacl_bootstrap_arm)
chromeos-chrome-54.0.2800.2_rc-r1: FAILED: nacl_bootstrap_arm/obj/native_client/src/trusted/service_runtime/linux/nacl_bootstrap_raw 
chromeos-chrome-54.0.2800.2_rc-r1: python ../../../../../../../home/chrome-bot/chrome_root/src/native_client/src/trusted/service_runtime/linux/ld_bfd.py --compiler arm-linux-gnueabihf-g++ -m armelf_linux_eabi --build-id -static -z max-page-size=0x1000 --defsym RESERVE_TOP=0x40002000 --script=/home/chrome-bot/chrome_root/src/native_client/src/trusted/service_runtime/linux/nacl_bootstrap.x -o /var/cache/chromeos-chrome/chrome-src-internal/src/out_daisy/Release/nacl_bootstrap_arm/obj/native_client/src/trusted/service_runtime/linux/nacl_bootstrap_raw --whole-archive /var/cache/chromeos-chrome/chrome-src-internal/src/out_daisy/Release/nacl_bootstrap_arm/obj/native_client/src/trusted/service_runtime/linux/libnacl_bootstrap_lib.a --no-whole-archive
chromeos-chrome-54.0.2800.2_rc-r1: /bin/sh: arm-linux-gnueabihf-g++: command not found
chromeos-chrome-54.0.2800.2_rc-r1: /bin/sh: arm-linux-gnueabihf-g++: command not found
chromeos-chrome-54.0.2800.2_rc-r1: /usr/x86_64-pc-linux-gnu/binutils-bin/2.25.51/ld.bfd.real: unrecognised emulation mode: armelf_linux_eabi
chromeos-chrome-54.0.2800.2_rc-r1: Supported emulations: elf_x86_64 elf32_x86_64 elf_i386 i386linux elf_l1om elf_k1om
chromeos-chrome-54.0.2800.2_rc-r1: Could not find ld: None
chromeos-chrome-54.0.2800.2_rc-r1: Could not find libgcc: None


I am a little puzzled by this. I thought we were not using clang to build chrome in the builder where this is coming from. Need to look deeper at this.