[ccache] How to omit caching of a specific compilation

[Anders Björklund]

Mats Nilsson wrote:
> Thank you very much!
>> Is there a way to instruct ccache to not cache the object file from a specific compilation?
>>
>      Look for the following configuration file options in the ccache(1) man
> page for disable, read_only, and read_only_direct to decide which one you
> need for your situation.

It would also be nice to know why it had to be disabled, if there is a 
bug in ccache. Normally caching a compilation shouldn't hurt anything...

Now, certain compilations (e.g. timestamps) one might to avoid compiling
just to not fill the cache with junk. But normally that doesn't happen*.

/Anders


* i.e. it's a bad idea anyway, for other reasons (reproducability etc)

See https://reproducible-builds.org/ for more on the particular subject.