Add CMake build directory patterns to .gitignore

[hebasto]

Whenever I work on changes that require comparison, such as benchmarking, I end up with two or more build directories that provide different binary variants simultaneously. Adding these build directories to .gitignore makes the workflow a bit easier.

Additionally, a trivial refactoring is included to reduce the code.

[hebasto]

The same pattern is used in Bitcoin Core.

[real-or-random]

Concept ACK

We could also get rid of build-aux entirely by moving the contents of the only file into configure.ac. I think that would be nice. build-aux can be confusing to people familiar only with CMake, and it hinders tab-completion with CMake dirs etc... What do you think?

[hebasto]

We could also get rid of build-aux entirely by moving the contents of the only file into configure.ac. I think that would be nice.

I think the main purpose of:

secp256k1/configure.ac

Line 22 in b6c2a3c

AC_CONFIG_AUX_DIR([build-aux])

is to keep the top level of the repo uncluttered. Without it, it would end up filled as follows:

$ ./autogen.sh | grep -v libtoolize
configure.ac:38: installing './ar-lib'
configure.ac:36: installing './compile'
configure.ac:23: installing './config.guess'
configure.ac:23: installing './config.sub'
configure.ac:26: installing './install-sh'
configure.ac:26: installing './missing'
Makefile.am: installing './depcomp'
parallel-tests: installing './test-driver'

build-aux can be confusing to people familiar only with CMake, and it hinders tab-completion with CMake dirs etc... What do you think?

The build-aux directory could be renamed. Perhaps to something like autotools-aux?

[real-or-random]

Oh sure! Even I forgot the main purpose of the directory.

The build-aux directory could be renamed. Perhaps to something like autotools-aux?

I like that suggestion.

[hebasto]

The build-aux directory could be renamed. Perhaps to something like autotools-aux?

I like that suggestion.

Thanks! Done.