zig cc and zig c++ do not use stdout with -o - arguments

[dasimmet]

Zig Version

0.14.0-dev.367+a57479afc

Steps to Reproduce and Observed Behavior

When running zig cc or zig c++ with -o -, arguments, the output should be written to stdout, like regular clang or even zig clang does.

With an empty test.h file:

zig c++ -E -x c++-header test.h -o -

this produces a file named - in the current working directory instead, which is especially annoying with running cmake, since it uses CC/CXX with -o - arguments to find compiler features and the c++ standard library.

Expected Behavior

clang-18 -E -x c++-header test.h -o -

zig [clang/c++/cc] -E -x c++-header test.h -o -

output:

# 1 "test.h"
# 1 "<built-in>" 1
# 1 "<built-in>" 3
# 454 "<built-in>" 3
# 1 "<command line>" 1
# 1 "<built-in>" 2
# 1 "test.h" 2