Get rid of reproducible build warning by removing build date & time from flatc version (#5086)
Get rid of reproducible build warning by removing build date & time from flatc version (#5086)

* disable reproducible build warning due to date/time macros

* wrapped GCC pragmas in #ifdef _GNUC_

* removed __DATE__ and __TIME__ macros from flatc.cpp

royalharsh/flatbuffers,pjulien/flatbuffers,pjulien/flatbuffers,evolutional/flatbuffers,pjulien/flatbuffers,DavadDi/flatbuffers,alexames/flatbuffers,stewartmiles/flatbuffers,evolutional/flatbuffers,DavadDi/flatbuffers,DavadDi/flatbuffers,google/flatbuffers,alexames/flatbuffers,royalharsh/flatbuffers,google/flatbuffers,evolutional/flatbuffers,pjulien/flatbuffers,alexames/flatbuffers,hgl888/flatbuffers,google/flatbuffers,evolutional/flatbuffers,evolutional/flatbuffers,stewartmiles/flatbuffers,stewartmiles/flatbuffers,alexames/flatbuffers,google/flatbuffers,stewartmiles/flatbuffers,royalharsh/flatbuffers,stewartmiles/flatbuffers,pjulien/flatbuffers,alexames/flatbuffers,alexames/flatbuffers,google/flatbuffers,DavadDi/flatbuffers,evolutional/flatbuffers,evolutional/flatbuffers,royalharsh/flatbuffers,royalharsh/flatbuffers,alexames/flatbuffers,alexames/flatbuffers,google/flatbuffers,stewartmiles/flatbuffers,stewartmiles/flatbuffers,google/flatbuffers,royalharsh/flatbuffers,alexames/flatbuffers,royalharsh/flatbuffers,royalharsh/flatbuffers,pjulien/flatbuffers,google/flatbuffers,evolutional/flatbuffers,pjulien/flatbuffers,pjulien/flatbuffers,evolutional/flatbuffers,google/flatbuffers,stewartmiles/flatbuffers,DavadDi/flatbuffers,alexames/flatbuffers,evolutional/flatbuffers,pjulien/flatbuffers,alexames/flatbuffers,hgl888/flatbuffers,google/flatbuffers,google/flatbuffers,stewartmiles/flatbuffers,royalharsh/flatbuffers,stewartmiles/flatbuffers,hgl888/flatbuffers,pjulien/flatbuffers,google/flatbuffers,hgl888/flatbuffers,google/flatbuffers,stewartmiles/flatbuffers,google/flatbuffers,pjulien/flatbuffers,stewartmiles/flatbuffers,evolutional/flatbuffers,alexames/flatbuffers,alexames/flatbuffers,evolutional/flatbuffers,alexames/flatbuffers,royalharsh/flatbuffers,hgl888/flatbuffers,stewartmiles/flatbuffers,google/flatbuffers,evolutional/flatbuffers,DavadDi/flatbuffers,alexames/flatbuffers,pjulien/flatbuffers,hgl888/flatbuffers