gummiboot: fix removal of loader entries

Stop using $PKGNAME (linux3.XX) in post-install since post-remove
gets $PKGNAME as linux through vkpurge.
midori: fix update-check
mdds: fix update-check
makeself: fix update-check
void-repo-nonfree: update for xbps-0.42.
void-repo-multilib: update for xbps-0.42.
backintime: update to 1.0.40.
CopyQ: update to 2.4.2.
build_style/fetch: non-global vars
cmake-gui: update to 3.0.2.
Cython: update to 0.21.1.
meld: update to 3.12.1.
meld: remove unnnecessary bdeps; use pycompile_module.
meld: make this work and add proper rdeps.
openjpeg: ignore 2.* versions in update-check
openmpi: update to 1.8.3.
pcsc-tools: update to 1.4.23.
xf86-input-wacom: update to 0.27.0.
xbps-src: libexec: simplify chdir to wrksrc/build_wrksrc.