CI: install byacc instead of bison on Arch

So we can test the byacc path as well as the bison one

ci/ciimage/arch/install.sh

@@ -9,7 +9,7 @@ source /ci/common.sh
 pkgs=(
   python python-pip pypy3
   ninja make git sudo fakeroot autoconf automake patch
-  libelf gcc gcc-fortran gcc-objc vala rust bison flex cython go dlang-dmd
+  libelf gcc gcc-fortran gcc-objc vala rust byacc flex cython go dlang-dmd
   mono boost qt5-base gtkmm3 gtest gmock protobuf gobject-introspection
   itstool glib2-devel gtk3 java-environment=8 gtk-doc llvm clang sdl2 graphviz
   doxygen vulkan-validation-layers openssh mercurial gtk-sharp-2 qt5-tools