安装nginx时出现In function ‘ngx_murmur_hash2’等错误

报错:

src/core/ngx_murmurhash.c: In function ‘ngx_murmur_hash2’:
src/core/ngx_murmurhash.c:37:11: error: this statement may fall through [-Werror=implicit-fallthrough=]
         h ^= data[2] << 16;
         ~~^~~~~~~~~~~~~~~~
src/core/ngx_murmurhash.c:38:5: note: here
     case 2:
     ^~~~
src/core/ngx_murmurhash.c:39:11: error: this statement may fall through [-Werror=implicit-fallthrough=]
         h ^= data[1] << 8;
         ~~^~~~~~~~~~~~~~~
src/core/ngx_murmurhash.c:40:5: note: here
     case 1:
     ^~~~

原因，是将警告当成了错误处理，打开/home/vagrant/nginx-1.11.2/objs/Makefile，
去掉CFLAGS中的-Werror
再重新make
-Wall 表示打开gcc的所有警告
-Werror，它要求gcc将所有的警告当成错误进行处理