Add get_pcre_version() and check_pcre()

[staticfloat]

To ensure that the pcre version is what we want.

I'm not sure if 8.31 is the actual minimum version number we support, it's just what I had on my machine.

[staticfloat]

For context/why this is needed: #3838 (comment)

[StefanKarpinski]

Seems reasonable to me.

[vtjnash]

julia$ export LD_LIBRARY_PATH=/opt/local/lib
....
julia> version_string = bytestring( ccall((:pcre_version, "libpcre"), Ptr{Uint8}, () ))
"8.33 2013-05-28"

julia> isabspath("/")
false

[staticfloat]

@vtjnash; I'm assuming that is meant to illustrate that although version 8.33 is being linked to, ismatch is still failing? There must be some configuration mismatch somewhere then. Brew's pcre configure line looks like this:

system "./configure", "--disable-dependency-tracking",
                          "--prefix=#{prefix}",
                          "--enable-utf8",
                          "--enable-unicode-properties",
                          "--enable-pcregrep-libz",
                          "--enable-pcregrep-libbz2",
                          "--enable-jit"

Macport's looks like this:

configure.args      --docdir=${prefix}/share/doc/${name}
                        --disable-silent-rules \
                        --enable-pcre16 \
                        --enable-pcre32 \
                        --enable-jit \
                        --enable-unicode-properties \
                        --enable-pcregrep-libz \
                        --enable-pcregrep-libbz2 \
                        --enable-pcretest-libedit

and Macports also contains this diff on the configure file which seems to take out some pthreads flags. Can you try changing the configure flags to those used by brew and seeing if the Macports pcre works then?

[JeffBezanson]

Can this go in the PCRE module?

[staticfloat]

I suppose that makes sense! However, we're hashing stuff out in #3838 to see if we can't make this detection more bulletproof. I'll reorganize once we have something that works.

Closing until then

[ViralBShah]

We should certainly bump the PCRE version if that helps.