Move linking LIBS to end of command

This PR moves the all linking `$(LIBS)` to the end of the command. Newer versions of `ld` on Linux (Ubuntu 12.04, for example) get a little finicky about flag ordering.

Resolves:
```shell
root@grapple:/opt/makeme/vendor/stltwalker# make
cc -std=c99 -g -O2 -I/opt/makeme/vendor/stltwalker/src  -Wall -Werror -o /opt/makeme/vendor/stltwalker/src/stl.o -c /opt/makeme/vendor/stltwalker/src/stl.c
cc -std=c99 -g -O2 -I/opt/makeme/vendor/stltwalker/src  -Wall -Werror -o /opt/makeme/vendor/stltwalker/src/matrix.o -c /opt/makeme/vendor/stltwalker/src/matrix.c
cc -std=c99 -g -O2 -I/opt/makeme/vendor/stltwalker/src  -Wall -Werror -o /opt/makeme/vendor/stltwalker/src/pack.o -c /opt/makeme/vendor/stltwalker/src/pack.c
cc -std=c99 -g -O2 -I/opt/makeme/vendor/stltwalker/src  -Wall -Werror -o /opt/makeme/vendor/stltwalker/src/dbg.o -c /opt/makeme/vendor/stltwalker/src/dbg.c
cc -std=c99 -g -O2 -I/opt/makeme/vendor/stltwalker/src  -Wall -Werror -o /opt/makeme/vendor/stltwalker/src/transform.o -c /opt/makeme/vendor/stltwalker/src/transform.c
cc -std=c99 -g -O2 -I/opt/makeme/vendor/stltwalker/src  -Wall -Werror -o src/stltwalker.o -c src/stltwalker.c
cc -std=c99 -g -O2 -I/opt/makeme/vendor/stltwalker/src  -Wall -Werror -o stltwalker.new  -lm /opt/makeme/vendor/stltwalker/src/stl.o /opt/makeme/vendor/stltwalker/src/matrix.o /opt/makeme/vendor/stltwalker/src/pack.o /opt/makeme/vendor/stltwalker/src/dbg.o /opt/makeme/vendor/stltwalker/src/transform.o src/stltwalker.o
/opt/makeme/vendor/stltwalker/src/stl.o: In function `v3_cross':
/opt/makeme/vendor/stltwalker/src/stl.c:43: undefined reference to `sqrtf'
/opt/makeme/vendor/stltwalker/src/transform.o: In function `init_transform_rotateX_f':
/opt/makeme/vendor/stltwalker/src/transform.c:135: undefined reference to `sincosf'
/opt/makeme/vendor/stltwalker/src/transform.o: In function `init_transform_rotateY_f':
/opt/makeme/vendor/stltwalker/src/transform.c:155: undefined reference to `sincosf'
/opt/makeme/vendor/stltwalker/src/transform.o: In function `init_transform_rotateZ_f':
/opt/makeme/vendor/stltwalker/src/transform.c:175: undefined reference to `sincosf'
collect2: ld returned 1 exit status
make: *** [stltwalker] Error 1
```