Remove unnecessary redefinitions of uint*_t types

[ptrcnull]

while the spec (ISO 9899:1999, 7.18.1.1) makes these typedefs optional, in practice they are defined in <stdint.h> for all supported platforms

meanwhile, types u_int*_t are BSDisms and might not exist, making the typedefs fail with error: unknown type name ‘u_int8_t’, e.g. on Solaris or musl libc

[ptrcnull]

as with #218, it's related to Firefox bugs 1962061 and 1964446

[RouHim]

Are there any plans to merge this?