clang-format removes spaces between throw and cast

[alanzhao1]

First reported in Chromium: https://crbug.com/1018187

Repro steps:

$ cat test_throw.cpp
void foo(int x) { throw (long) x; }

$ clang-format test_throw.cpp

Expected behavior:
clang-format should not remove the space before throw and (long)

Actual behavior:

void foo(int x) { throw(long) x; }

It seems that clang-format is treating throw (long) as a function-style construct instead of a cast.

[llvmbot]

@llvm/issue-subscribers-clang-format

[rymiel]

Differential: https://reviews.llvm.org/D132762