Two minor fixes necessary for successful compilation with g++15

[The9Cat]

Changes

1. Explicit integer types are now defined in <cstdint> and this header needs to be included for things like uint*_t.
2. The old GaussCore code uses some type redefinition trickery which is now illegal in g++15. This results from gcc-15 supporting C23 which adds bool as an official key word so typedef int bool; is now an error. Updated by removing theat typedef in favor of a real bool C17 bool type.

Notes

I have not checked gcc 15 with Cuda

[Copilot]

Pull Request Overview

This PR addresses compilation issues with g++15 by fixing header dependencies and removing deprecated type redefinition patterns.

• Adds necessary <cstdint> includes for explicit integer types required by g++15
• Replaces custom boolean type definitions with standard C <stdbool.h> implementation
• Sets C standard to C17 in CMake configuration

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
include/cxxopts.H	Adds <cstdint> include for uint types
exputil/GaussCore.c	Replaces custom bool typedef with standard <stdbool.h>
expui/ParticleIterator.H	Adds <cstdint> include for integer types
CMakeLists.txt	Sets C standard to C17 for stdbool.h compatibility

Comments suppressed due to low confidence (1)

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[michael-petersen]

All seems good here, I've compiled on MacOS with no trouble.