[Bug]: compilation failure on HaikuOS

### Describe the issue

### Steps to reproduce the problem

cmake -DCMAKE_BUILD_TYPE=Release -Bbuild -S.
cmake --build build -- -j64

### What version of Abseil are you using?

git latest

### What operating system and version are you using?

HaikuOS 59199

### What compiler and version are you using?

gcc 13.3.0

### What build system are you using?

cmake + gnumake

### Additional context

i just made it `return 0;` and builds fine, obviously incorrect