Remove HAVE_LONG_LONG_INT
The presence of long long int is now implied in the requirement for
C99 and the configure check for the same.
We keep the define hard-coded in ecpg_config.h for backward
compatibility with ecpg-using user code.
Discussion: https://www.postgresql.org/message-id/flat/
5cdd6a2b-b2c7-c6f6-344c-
a406d5c1a254%402ndquadrant.com