Use version-script with cmake builds

[opoplawski]

This is an attempt to resurrect symbol versioning and fix #775 . One problem is the new unit tests that link to libclamav and test internal functions do not have access to the symbols. I started adding them to the symbol map, but I don't think this is the proper solution. I think instead there perhaps be a static library that is used for the unit tests?

[opoplawski]

We're going to need a check for the existence of version-script I think - there are some examples out there like https://github.com/jrl-umi3218/jrl-cmakemodules/blob/master/version-script.cmake

[val-ms]

I am also seeing failures in our internal jenkins for our statically linked DEB and RPM builds with this failure:

/root/.mussels/install/host-static/lib/libxml2.a(xmlIO.c.o): In function `xmlGzfileOpenW':
xmlIO.c:(.text+0x25a): undefined reference to `gzdopen'
xmlIO.c:(.text+0x298): undefined reference to `gzopen64'
/root/.mussels/install/host-static/lib/libxml2.a(xmlIO.c.o): In function `xmlCreateZMemBuff':
xmlIO.c:(.text+0xa8c): undefined reference to `deflateInit2_'
xmlIO.c:(.text+0xaa3): undefined reference to `crc32'
xmlIO.c:(.text+0xb46): undefined reference to `deflateEnd'
xmlIO.c:(.text+0xbc1): undefined reference to `deflateEnd'
/root/.mussels/install/host-static/lib/libxml2.a(xmlIO.c.o): In function `xmlGzfileClose':
xmlIO.c:(.text+0xbe5): undefined reference to `gzclose'
/root/.mussels/install/host-static/lib/libxml2.a(xmlIO.c.o): In function `xmlGzfileRead':
xmlIO.c:(.text+0xc25): undefined reference to `gzread'
/root/.mussels/install/host-static/lib/libxml2.a(xmlIO.c.o): In function `xmlGzfileWrite':
xmlIO.c:(.text+0xd95): undefined reference to `gzwrite'
/root/.mussels/install/host-static/lib/libxml2.a(xmlIO.c.o): In function `xmlGzfileOpen':
xmlIO.c:(.text+0x16b5): undefined reference to `gzdopen'
xmlIO.c:(.text+0x1714): undefined reference to `gzopen64'
xmlIO.c:(.text+0x1776): undefined reference to `gzdopen'
xmlIO.c:(.text+0x1828): undefined reference to `gzopen64'
/root/.mussels/install/host-static/lib/libxml2.a(xmlIO.c.o): In function `__xmlParserInputBufferCreateFilename':
xmlIO.c:(.text+0x1c93): undefined reference to `gzdirect'
/root/.mussels/install/host-static/lib/libxml2.a(xmlIO.c.o): In function `xmlIOHTTPWrite':
xmlIO.c:(.text+0x2a56): undefined reference to `deflate'
xmlIO.c:(.text+0x2acb): undefined reference to `deflate'
xmlIO.c:(.text+0x2bea): undefined reference to `crc32'
/root/.mussels/install/host-static/lib/libxml2.a(xmlIO.c.o): In function `xmlIOHTTPCloseWrite':
xmlIO.c:(.text+0x32a1): undefined reference to `deflate'
xmlIO.c:(.text+0x33f7): undefined reference to `deflateEnd'
/root/.mussels/install/host-static/lib/libxml2.a(xmlIO.c.o): In function `xmlIOHTTPOpenW':
xmlIO.c:(.text+0x3798): undefined reference to `deflateEnd'
xmlIO.c:(.text+0x37e1): undefined reference to `deflateEnd'
/root/.mussels/install/host-static/lib/libxml2.a(nanohttp.c.o): In function `xmlNanoHTTPFreeCtxt':
nanohttp.c:(.text+0x405): undefined reference to `inflateEnd'
/root/.mussels/install/host-static/lib/libxml2.a(nanohttp.c.o): In function `xmlNanoHTTPRead':
nanohttp.c:(.text+0xe4f): undefined reference to `inflate'
/root/.mussels/install/host-static/lib/libxml2.a(nanohttp.c.o): In function `xmlNanoHTTPMethodRedir':
nanohttp.c:(.text+0x1cfb): undefined reference to `inflateInit2_'
collect2: error: ld returned 1 exit status
[ 99%] Built target clamdtop
unit_tests/CMakeFiles/check_clamav.dir/build.make:402: recipe for target 'unit_tests/check_clamav' failed
make[2]: *** [unit_tests/check_clamav] Error 1
CMakeFiles/Makefile2:2099: recipe for target 'unit_tests/CMakeFiles/check_clamav.dir/all' failed
make[1]: *** [unit_tests/CMakeFiles/check_clamav.dir/all] Error 2

I'm not sure why.

[val-ms]

We have limited time left before the 1.0.0 stable release. We're aiming to publish it one week from today and so are hoping to have everything wrapped up and ready to go by end of business on Wednesday, to account for the american thanksgiving holiday weekend.
That is -- I have low expectations that we'll be able to solve this in time.

To resolve your concern about the ABI/namespace change in time for the 1.0.0 release, I have placed a PR to bump the SO version: #778

[val-ms]

I just rebased this PR with the upstream main branch so it will pass tests in the internal Jenkins pipeline.

[val-ms]

This PR is also missing using the libclamunrar.map as seen in #816. I have a commit in a personal/internal branch that i'm testing and if testing goes well, I'll push it here along with pushing a commit that resolves the linking issue I observed with the check_clamav unit test program when linking a static libxml2.a library.