Latest installer version is out of date comapred to archive
See CMakeLists.txt. You do typo again with copy-paste. Remove "+" before endif
Fix typo in build files
You need run pkg-config from mingw shell not msys one.
Well you may need install more tools: try "pacman -S base-devel" and then try build...
Check our wiki and create this packages yourself - this is the fastest variant
You need pass proper "--build", "--host" and "--target" to configure
There are no yet new installer with fixed pacman so you need after clean install...