build: add a really quiet mode for compilation

[lcheylus]

With QUIET=true, build with make is really quiet:

• no initial header with version / OS / arch
• no display of build steps with colors
• no display of build steps with % and time used
• no display of total time to complete build
• with VERBOSE=true, only logs from compiler

Fix aristocratos/btop#769

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Build with GNU make and tests OK on OpenBSD current/amd64 and Linux Debian/testing with:

• clang++ v16
• g++ v11

Only logs from compiler displayed during build with QUIET=true VERBOSE=true make

[aristocratos]

add a really quiet mode for compilation

This doesn't add a really quiet mode, it changes the current quiet mode.

[lcheylus]

add a really quiet mode for compilation

This doesn't add a really quiet mode, it changes the current quiet mode.

OK, I agree => PR closed.