Clean up code in inifile.c
fix Issue 12622 - Purity, @safe not checked for pointers to functions
Merge pull request #3489 from 9rnsr/fix12622

Issue 12622 - Purity, @safe not checked for pointers to functions
fix Issue 12689 - [CTFE] assigning via pointer from 'in' expression doesn't work
Merge pull request #3521 from 9rnsr/fix12689

Issue 12689 - [CTFE] assigning via pointer from 'in' expression doesn't work
Merge pull request #3354 from yebblies/inifile

[cleanup] Untangle the rat's nest in inifile.c