For the most part no behavior change, except that we now pass
-Wno-implicit-const-int-float-conversion and -Wno-literal-suffix
only to clang and gcc each in both lagom and serenity builds,
while we previously passed them to both in lagom builds (and
passed them to one each in serenity builds). The former is
a clang flag, the latter a gcc flag, but since we also use
-Wno-unknown-warning-option it doesn't really matter.
8f988b7bae