mod_substitute: use local/native LF for splitting

On platforms where the APR_ASCII_LF != '\n', like EBCDIC systems,
strmatch or pcre patterns from the source or config will be in
the native encoding, and this module will really only work on 
content in the native encoding.

(mod_substitute runs before mod_charset_lite for a similar reason)

I thought #if APR_CHARSET_EBCDIC or even #ifdef __MVS__ was overkill
here. 



(CTR due to ebcdic-only)


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1794856 13f79535-47bb-0310-9956-ffa450edef68