[clang-format] [PR25010] AllowShortIfStatementsOnASingleLine not working if an "else...

[clang-format] [PR25010] AllowShortIfStatementsOnASingleLine not working if an "else" statement is present

Summary:
Addressing: PR25010 - https://bugs.llvm.org/show_bug.cgi?id=25010

Code like:

```
    if(true) var++;
    else  {
        var--;
    }
```

is reformatted to be

```
  if (true)
    var++;
  else {
    var--;
  }
```

Even when `AllowShortIfStatementsOnASingleLine` is true

The following revision comes from a +1'd suggestion in the PR to support AllowShortIfElseStatementsOnASingleLine

This suppresses the clause prevents the merging of the if when there is a compound else

Reviewers: klimek, djasper, JonasToth, alexfh, krasimir, reuk
Reviewed By: reuk
Subscribers: reuk, Higuoxing, jdoerfert, cfe-commits
Tags: #clang-tools-extra
Differential Revision: https://reviews.llvm.org/D59087

llvm-svn: 356031