在我的山狮终端上运行 brew doctor ，我收到以下错误：
Warning: /usr/local/etc isn't writable.
This can happen if you "sudo make install" software that isn't managed
by Homebrew.
If a brew tries to write a file to this directory, the install will
fail during the link step.
You should probably `chown` /usr/local/etc
Warning: Some directories in /usr/local/share/man aren't writable.
This can happen if you "sudo make install" software that isn't managed
by Homebrew. If a brew tries to add locale information to one of these
directories, then the install will fail during the link step.
You should probably `chown` them:
/usr/local/share/man/man8
Warning: Your XQuartz (2.7.2) is outdated
Please install XQuartz 2.7.4.
Warning: Unbrewed dylibs were found in /usr/local/lib.
If you didn't put them there on purpose they could cause problems when
building Homebrew formulae, and may need to be deleted.
Unexpected dylibs:
/usr/local/lib/libicudata.49.1.2.dylib /usr/local/lib/libicui18n.49.1.2.dylib /usr/local/lib/libicuio.49.1.2.dylib /usr/local/lib/libicule.49.1.2.dylib /usr/local/lib/libiculx.49.1.2.dylib /usr/local/lib/libicutest.49.1.2.dylib /usr/local/lib/libicutu.49.1.2.dylib /usr/local/lib/libicuuc.49.1.2.dylib
Warning: Unbrewed .pc files were found in /usr/local/lib/pkgconfig.
If you didn't put them there on purpose they could cause problems when
building Homebrew formulae, and may need to be deleted.
Unexpected .pc files:
/usr/local/lib/pkgconfig/icu-i18n.pc /usr/local/lib/pkgconfig/icu-io.pc /usr/local/lib/pkgconfig/icu-le.pc /usr/local/lib/pkgconfig/icu-lx.pc /usr/local/lib/pkgconfig/icu-uc.pc
Warning: Unbrewed static libraries were found in /usr/local/lib.
If you didn't put them there on purpose they could cause problems when
building Homebrew formulae, and may need to be deleted.
Unexpected static libraries:
/usr/local/lib/libc-client.a
Warning: Homebrew's sbin was not found in your path.
Consider amending your PATH variable so it contains:
/usr/local/sbin
我该如何解决这些错误？修复它们是否至关重要，否则我可能会忽略它们？谢谢你。