These defines have been present since day one of the git repo in 2006.
The log message of the cvs commit which introduced them back then
just states "activate the source browser", so it will have to remain
a mystery why __GNUC__ and __GNUC_MINOR__ needed to be predefined.
# recursively expanded use the := operator instead of the = operator.
# This tag requires that the tag ENABLE_PREPROCESSING is set to YES.
-PREDEFINED = __GNUC__=4 \
- __GNUC_MINOR__=4
+PREDEFINED =
# If the MACRO_EXPANSION and EXPAND_ONLY_PREDEF tags are set to YES then this
# tag can be used to specify a list of macro names that should be expanded. The