problems configuring with pcre-4.5 installed

[Jskud]

A build from source of Octave 2.9.15 does not detect nor use the
installed pcre-4.5 package.

I have the pcre rpms installed

    pcre-4.5-3.2.RHEL4.i386.rpm
    pcre-devel-4.5-3.2.RHEL4.i386.rpm

and they put the pcre.h header file in /usr/include/pcre/pcre.h.

I built octave-2.9.15 from the source distribution, and configure looks
in /usr/include, not /usr/include/pcre, and so configure does not find
pcre.h.

Also, pcre provides pcre-config, but the configure.in script defines
"WITH_PCRE_CONFIG=no" before checking for it, and so does not find it.

    ### Check for pcre/regex library.
    AC_SUBST(REGEX_LIBS)
    WITH_PCRE_CONFIG=no
    AC_CHECK_HEADER(pcre.h, WITH_PCRE=yes, WITH_PCRE=no)
    if test $WITH_PCRE = no ; then
      AC_CHECK_PROG(WITH_PCRE_CONFIG, pcre-config, yes, no)
      if test $WITH_PCRE_CONFIG = yes ; then
        WITH_PCRE=yes
      fi
    fi

And if the configure script were to find pcre-config, it appears not to
use the pcre-config provided include path when compiling, and so would
likely not see pcre.h, either in the configure, or during a build.

[And it's not obvious how to gently add -I/usr/include/pcre to the
builds.]

A workaround (for those able to whack their /usr/include directory) is
to add a link in /usr/include to pcre/pcre.h as pcre.h -- then, Octave
will configure and build with pcre successfully.

/Jskud