use constexpr on various

otherwise gcc will put this into the read/write section
of the object file.

Change-Id: I142eb7b3cbe1c50aa8274c7983f9773d148a5b09
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/188329
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

unotools/source/misc/fontcvt.cxx

@@ -1304,7 +1304,7 @@ struct RecodeTable { const char* pOrgName; ConvertChar aCvt;};
 
 }
 
-const RecodeTable aStarSymbolRecodeTable[] =
+constexpr RecodeTable aStarSymbolRecodeTable[] =
 {
     // the first two entries must be StarMath and StarBats; do not reorder!
     // reason: see CreateFontToSubsFontConverter method