Add ap_size_parameter_parse(), a helper to parse a configuration value
as an apr_off_t, which fails on trailing characters and on overflow.
The range of the value remains up to the directive.
Use it for configuration directives which parsed such values in
different ways, some of them accepting trailing characters or doing no
checks at all: LimitRequestBody (unchanged behavior), ScriptLogLength,
ScriptLogBuffer, DavQuota, BufferSize, AuthFormSize, and the
mod_cache_disk and mod_cache_socache size and time directives.
GitHub: closes#829
git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1939129 13f79535-47bb-0310-9956-ffa450edef68