configure.in: Include <stdint.h> and <inttypes.h> when checking for double storage...

configure.in: Include <stdint.h> and <inttypes.h> when checking for double storage layout.

Some systems, for example Solaris 9, don't have <stdint.h> and define
`uint32_t' via <inttypes.h> instead. Be more permissive by including
both header files when checking how doubles are stored in memory.