Add *.m4 to svn:auto-props, make sure all m4 macros have svn:eol-style native

As a follow-up to the EOL style fix in r1883388 in build/ac-macros/macosx.m4,
found we had additional m4 macros without svn:eol-style native. Fixing them
and adding it to svn:auto-props:

* .
  (svn:auto-props): Add filter for *.m4

* build/ac-macros/ax_boost_base.m4
* build/ac-macros/ax_boost_unit_test_framework.m4
* build/ac-macros/compiler.m4
* build/ac-macros/libsecret.m4
* build/ac-macros/lz4.m4
* build/ac-macros/py3c.m4
* build/ac-macros/utf8proc.m4
  Add svn:eol-style native


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1883390 13f79535-47bb-0310-9956-ffa450edef68