Added support ccache for speedup compilation on Linux

[GermanAizek]

@HansKristian-Work more information:
https://ccache.dev/
https://en.wikipedia.org/wiki/Ccache

[cdavis5e]

Historically, CMake build systems that use ccache(1) automatically have caused problems for me, e.g. when installing ports from source in MacPorts. Then again, I suppose it's easy enough to work around that with -DCCACHE_FOUND=NO.

[cdavis5e]

After the find_program() above, the variable CCACHE_FOUND will contain the full pathname of the ccache program. You should probably use it, instead of assuming that ccache will be in the user's PATH.

[HansKristian-Work]

Is there really a point adding this? This isn't a massive project where ccache really helps. At the very least, it should be opt-in, not enabled by default.

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