sysutils/passwordsafe: fix build on powerpc64 elfv2

Switch to GCC on powerpc64, due to (already reported upstream) clang bug:
Assertion failed: (CAT && "unexpected type for array initializer"), function VisitCXXNewExpr, file /poudriere/jails/powerpc64-head/usr/src/contrib/llvm-project/clang/lib/AST/ExprConstant.cpp, line 8690.