**ERROR: Ninja build tool not found.

| if which ninja-build ;\
| then \
| ln -s `which ninja-build` bin/ninja ;\
| else \
| echo "***ERROR: Ninja build tool not found." 1>&2 ;\
| exit 1;\
| fi;\
| fi
| ***ERROR: Ninja build tool not found.
| make: *** [tools] Error 1
| WARNING: /home/ubuntu/yocto/build_bin/tmp/work/x86_64-linux/legato-tools/git-r0/temp/run.do_compile.104989:1 exit 2 from
| VERBOSE=1 make tools
| ERROR: Function failed: do_compile (log file is located at /home/ubuntu/yocto/build_bin/tmp/work/x86_64-linux/legato-tools/git-r0/temp/log.do_compile.104989)
ERROR: Task 1282 (/home/ubuntu/yocto/meta-swi/common/recipes-legato/legato-af/legato-tools_git.bb, do_compile) failed with exit code '1

编译高通平台的时候，碰到这个问题。

于是 要安装 

apt-get install ninja-build，就可以了。