Merge pull request multi-build#138 from radarhere/arb

Updated arb to 2.12.0

Author: radarhere

tests/test_library_builders.sh

@@ -12,7 +12,7 @@ suppress build_libpng
 suppress build_libwebp
 suppress build_szip
 suppress build_swig
-suppress build_github fredrik-johansson/arb 2.11.1
+suppress build_github fredrik-johansson/arb 2.12.0
 suppress build_flex
 suppress build_openblas