Adventures in ports, chapter 364135

[george+freebsd at m5p.com]

mail/thunderbird does not compile on 8.4-STABLE because base gcc is too
old.  Adding "USE_GCC= 4.7+" fixes the issue, but then of course it
won't compile on a system without gcc at all.  Is there an idiom to say
"Use clang, but if you use gcc, use at least 4.7"?

portmaster and databases/firebird25-client don't work well together; I
encountered the config dialog multiple times in the course of one build.
Presumably some step of the build is deleting the cached option file.

It would be nice for devel/qt5 to have a more granular database option
than the all-in-one; something like:

OPTIONS_DEFINE= SQL_IBASE SQL_MYSQL SQL_ODBC SQL_POSTGRES SQL_SQLITE2 \
                SQL_SQLITE3 TOOLS
SQL_PLUGINS_USE=
.if ${PORT_OPTIONS:MIBASE}
SQL_PLUGINS_USE=sql-ibase
.endif
.if ${PORT_OPTIONS:MMYSQL}
SQL_PLUGINS_USE=sql-mysql
.endif
.if ${PORT_OPTIONS:MODBC}
SQL_PLUGINS_USE=sql-odbc
.endif
.if ${PORT_OPTIONS:MPOSTGRES}
SQL_PLUGINS_USE=sql-pgsql
.endif
.if ${PORT_OPTIONS:MSQLITE2}
SQL_PLUGINS_USE=sql-sqlite2
.endif
.if ${PORT_OPTIONS:MSQLITE3}
SQL_PLUGINS_USE=sql-sqlite3
.endif

It was a bit of a shock to get mysql, odbc, and sqlite2 built when all I
am really interested in are postgres and sqlite3!              -- George