Ambiguous expansion of macro `SWIFT_ENUM` in generated headers

[devioustree]

When using frameworks compiled with pre-5.8 compilers it can be trivial to have conflicting definitions of the SWIFT_ENUM macro in the generated Swift header. I believe this is a similar issue to #63338

My guess is that the new ClangMacros.def introduced in #59072 has accidentally omitted a space: https://github.com/apple/swift/blob/75f53a9b1923e891985734ea6ac6f4cae4d91603/include/swift/PrintAsClang/ClangMacros.def#L178

_name: _type used to be _name : _type (note the space before :)

[AnthonyLatsis]

cc @QuietMisdreavus

[QuietMisdreavus]

Nice catch! I've opened #63902 to fix this.