Imported from GitHub PR https://github.com/abseil/abseil-cpp/pull/1739

GCC 15 will no longer include <cstdint> by default, resulting in build failures in projects that do not explicitly include it.

Merge faf1b03a591f06933da02976119da5743f428e4f into 9cb5e5d1

Merging this change closes #1739

COPYBARA_INTEGRATE_REVIEW=https://github.com/abseil/abseil-cpp/pull/1739 from csfore:gcc-15-fix faf1b03a591f06933da02976119da5743f428e4f
PiperOrigin-RevId: 659637669
Change-Id: If14cb0e3522774cb700bd5a74abffb75feb7a0f5