Change order of objects and libraries

Most modern distros have the --as-needed flag activate in the gcc
toolchain. This means that placing the object files after the libraries
will let the linking fail with undefined references.
Use pkg-config to find blitz

The modern way to find a library it to use pkg-config instead of
hardcoding the path to the library.
Merge pull request #1 from wpoely86/master

Two small fixes in the makefile