The pcre source distribution, by default, installed its header into
$PREFIX/include like almost all other software.  The Fedora pcre-devel
RPM place these files in $PREFIX/include/pcre instead.

This location is non-standard, not the default for the upstream
package, and (to my knowlege) not shared by any other platforms that
ship pcre.  It forces software to detect and configure Redhat-specific
include paths and/or do brain damage like:

#ifdef REDHAT_PCRE
#include <pcre/pcre.h>
#else
#include <pcre.h>
#endif

This should be simple to fix.