想用cmake做交叉编译，可是glib安装不成功

smallfish

cmake已经安装完，编译程序的时候提示:
configure: error: Could not find a glib-compile-schemas in your PATH

好像是glib安装的不好，安装glib的时候提示：
configure: error: Package requirements (libffi >= 3.0.0) were not met:

No package 'libffi' found

Consider adjusting the PKG_CONFIG_PATH environment variable if you
installed software in a non-standard prefix.

Alternatively, you may set the environment variables LIBFFI_CFLAGS
and LIBFFI_LIBS to avoid the need to call pkg-config.
See the pkg-config man page for more details.

我安装了libffi，用源码方式，在/usr下，但是在编译glib的时候指定目录也不行
glib-2.32.2]# ./configure --with-libffi=/usr

不知道应该如何指定路径？