My summary of this:
1) Maintainer tag: It is a comment - makepkg does not care so nor
should you
2) $foo vs ${foo} : they do the same thing (except in rare cases where
brackets are needed...) - makepkg does not care so nor should you.
3) "$srcdr" vs $srcdir. The quotes are good for people who build in
directories with spaces in their name - so it may be good to use
quotes. But I don't care about people who use spaces in directory
names, so I am not going to do this. Note the prototype does include
quotes...
4) $startdir/src vs $srcdir. $srcdir is correct. As stated in the
PKGBUILD man page, there is no guarantee that these will continue to
point at the same directory in future pacman versions.
Allan