checkSpace.pl: clean up our list of types
checkSpace.pl has a list of types that are returned from function pointers, and uses it so that we don't complain about code like this:
bool (*eq)(const void *a, const void *b);
(Without recognizing that bool is a type, practracker would think that we were calling a function named "bool", and complain that we had a space after a function call.)
In their review for #30864 (moved), catalyst notes that the current code in checkSpace.pl for this is unweildy, and suggests that we use a list instead. I concur.