Fix page cache .htaccess for Windows

[nigrosimone]

On Windows OS the .htaccess section for page cache core module has a wrong path into the rule:

RewriteCond "%{DOCUMENT_ROOT}C:/DevEnv/htdocs/www.wordpress.local/wp-content/cache/page_enhanced/%{HTTP_HOST}/%{REQUEST_URI}/_index%{ENV:W3TC_PREVIEW}.html%{ENV:W3TC_ENC}" -f

this happened because w3tc into the .htaccess generation for page cache rules works in a linux style only.

the fix is transform the windows path in a linux path style

$document_root = str_replace('\\', '/', Util_Environment::document_root());

this fix the issue and now the rule is right:

RewriteCond "%{DOCUMENT_ROOT}/wp-content/cache/page_enhanced/%{HTTP_HOST}/%{REQUEST_URI}/_index%{ENV:W3TC_PREVIEW}.html%{ENV:W3TC_ENC}" -f