Setup gclient cache and ccache

[mrdimidium]

Adds a cache for gclient sync and ccache for V8 compilation. Flags are disabled by default.

Try locally:

# clenup build directory
rm -rf .lp-cache .zig-cache zig-out

# Build and warmup cache
zig build -Dgit_cache_dir="$HOME/.cache/gclient" -Dcc_wrapper="ccache"

# check that cache exists
du -sh ~/.cache/gclient
du -sh ~/.cache/ccache
ccache -s

# remove build in v8 dir and build again with cache
rm -rf .lp-cache .zig-cache zig-out
zig build -Dgit_cache_dir="$HOME/.cache/gclient" -Dcc_wrapper="ccache"

[krichprollsch]

Looks nice, but when removing .lp-cache the 2nd build, I still had the Bootstrapping V8 14.0.365.4 in /tmp/zig-v8-fork/.lp-cache/v8-14.0.365.4 (this will take a while)... step to do.
I guess it's expected?
After he cache worked in the same clone dir.

But I tested to build using zig build -Dgit_cache_dir="$HOME/.cache/gclient" -Dcc_wrapper="ccache" with a fresh clone, and it missed the cache to make a full rebuild. Any idea why?

[krichprollsch]

@mrdimidium would you like to rebase this one please?

[mookums]

Are we still planning on merging this? cc_wrapper would be nice.