- Mention in the CMake configuration documentation that LLVM builds, support the use of ccache.
- Use CCACHE_MAXSIZE instead of CCACHE_SIZE. The former is recognized by ccache, not the latter.
- Rename the LLVM CMake configuration variable to reflect that change: LLVM_CCACHE_SIZE -> LLVM_CCACHE_MAXSIZE
I know off-list I had suggested not bothering with detailed descriptions of LLVM_CCACHE_SIZE and LLVM_CCACHE_DIR, but now I am not so sure. If those variables map directly to ccache command-line arguments, we should say that here, and people can figure out how to set them by looking at the appropriate help. If the variables are more complicated, we should add separate entries for them in this doc.