swift

cb881979 - [NFC] Include <cstdint> in headers that use fixed-width integer types (#93104)

[NFC] Include <cstdint> in headers that use fixed-width integer types (#93104) ReferenceCounting.h and SILTypeProperties.h use uint8_t and uint16_t but relied on their includers to provide <cstdint>. Add the includes to fix build with libstdc++ 15.