patch needed to create libsvm.so

@tstrempel are these changes needed for the intel version of LIBSVM too? if so, please update that easyconfig as well.

I don't use the intel toolchain, so I can't say this for certain.
I'll update the intel easyconfigs after this pull request is accepted.

I prefer to have them both in the same PR. If you add the updated intel version, I or someone else can test it for you.

@smoors I updated the LIBSVM-3.23-intel-2018b.eb EasyConfig with the patch

Test report by @zao
FAILED
Build succeeded for 1 out of 2 (2 easyconfigs in this PR)
freja - Linux ubuntu 18.04, Intel(R) Core(TM) i7-8700K CPU @ 3.70GHz, Python 2.7.17
See https://gist.github.com/3ab2c93a3b54faf1347832fcaa034601 for a full test report.

Ignore the intel/2018b part of my test report, the machine cannot run such an old Intel compiler. 🤡
The foss part built fine.

Test report by @smoors
SUCCESS
Build succeeded for 2 out of 2 (2 easyconfigs in this PR)
node377.hydra.os - Linux centos linux 7.7.1908, Intel(R) Xeon(R) Gold 6148 CPU @ 2.40GHz, Python 2.7.5
See https://gist.github.com/614953faf852e1916d1276dbbc0911de for a full test report.

Going in, thanks @tstrempel!