Use file sanity checking code of RPM instead of POPT

     Change: stick-with-rpm-file-sanity-checking
     Purpose: Use file sanity checking code of RPM instead of POPT
     Reason: POPT >= 1.15 contains the poptSaneFile() function which
                     is equivalent to rpmSecuritySaneFile(). And POPT >=
                     1.15 also contains a poptReadConfigFiles() which
                     returns POPT_ERROR_BADCONFIG in case poptSaneFile()
                     says a file is not sane. This is all fine from a
                     raw sanity checking point of view. Unfortunately,
                     in the error reporting it is absolutely vital to
                     know _WHICH_ file is considered insecure. Until
                     POPT provides an error reporting callback or other
                     means for RPM to provide again reasonable warning
                     messages, we stick with the RPM sanity checking
                     code. So, this is not because OpenPKG is using
                     POPT < 1.15, but because we need proper warning
                     messages!