title: pkg-config fails to find package under sysroot directory
body: <p>Can anyone please tell me why this might fail:</p>
  
  <pre><code>afeder@ubuntu:~/android/toolchain/sysroot$ ls $PKG_CONFIG_SYSROOT_DIR/usr/local/lib/pkgconfig/mozjs185.pc
  /home/afeder/android/toolchain/sysroot/usr/local/lib/pkgconfig/mozjs185.pc
  
  afeder@ubuntu:~/android/toolchain/sysroot$ pkg-config mozjs185 --cflags
  Package mozjs185 was not found in the pkg-config search path.
  Perhaps you should add the directory containing `mozjs185.pc'
  to the PKG_CONFIG_PATH environment variable
  No package 'mozjs185' found
  </code></pre>
  
  <p>According to man <a href="https://linux.die.net/man/1/pkg-config" rel="nofollow noreferrer"><code>pkg-config(1)</code></a>, <code>/usr/local/lib/pkgconfig</code> is supposed to be one of the default search paths.</p>