Makefile: Move libraries includes in LDFLAGS at the end

[rapgenic]

As of now I cannot compile vampy in my ArchLinux system with the current Makefile, unless I change the following line:

https://github.com/c4dm/vampy/blob/e8a8cfb1f167f8d351ffef2daca00f5413b7c62e/Makefile.linux#L9

putting -lvamp-sdk -lpython2.7 -lpthread at the end of the variable.

See this StackOverflow question for why this seems to be happening.