LALPulsar build failures with GCC8

I'd like to make sure that LALSuite builds using GCC8 for O3, this is the default compiler on Debian Buster, and will be the default compiler in Ubuntu 18.10. Several users are already running into GCC8 releated problems and it is only a matter of time before more users start running into these problems.

FITSFileIO.c: In function 'CheckFITSKeyword':
FITSFileIO.c:232:48: error: '%s' directive output may be truncated writing up to 74 bytes into a region of size 66 [-Werror=format-truncation=]
     snprintf( keyword, FLEN_KEYWORD, "HIERARCH %s", buf );
                                                ^~   ~~~
FITSFileIO.c:232:5: note: 'snprintf' output between 10 and 84 bytes into a destination of size 75
     snprintf( keyword, FLEN_KEYWORD, "HIERARCH %s", buf );
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
FITSFileIO.c: In function 'XLALFITSHeaderWriteGPSTime':
FITSFileIO.c:1516:52: error: ' GPS' directive output may be truncated writing 4 bytes into a region of size between 1 and 75 [-Werror=format-truncation=]
   snprintf( keyword_gps, sizeof( keyword_gps ), "%s GPS", keyword );
                                                    ^~~~
FITSFileIO.c:1516:3: note: 'snprintf' output between 5 and 79 bytes into a destination of size 75
   snprintf( keyword_gps, sizeof( keyword_gps ), "%s GPS", keyword );
   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

SFTfileIO.c: In function 'XLALGetMultiSFTCatalogView':
SFTfileIO.c:1665:7: error: 'strncpy' output may be truncated copying 3 bytes from a string of length 63 [-Werror=stringop-truncation]
       strncpy( name, catalog->data[k].header.name, 3 );
       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~