lpc1768: cleanup Makefile

`cpu/lpc1768/Makefile` contains many lines that don't belong into this
file, but the maybe `Makefile.include`. Either way, this Makefile is
never called with these goals.
native: implement hwtimer removal
cpu cortex-m3_common: cleanup thread_arch.c
cpu - sam3x8e: added switch for newlib-nano specs
cpu - sam3x8e: fixed vtimer, added timer_set_absolute
Merge pull request #1356 from haukepetersen/fix_sam3x_newlibnano

cpu - sam3x8e: added switch for newlib-nano specs
Merge pull request #1357 from haukepetersen/fix_cortexm3_threading

cpu: cortex-m3_common: cleanup thread_arch.c
Introducing a source routing header for RPL.
Merge pull request #1218 from fabianbrandt/srh_rpl

Introducing a source routing header for RPL.
boards: removed -lto flag and cleanup for udoo&arduino due
Merge pull request #1365 from haukepetersen/fix_cortexm3_ltoflag

boards: removed -lto flag and cleanup for udoo&arduino due
Merge pull request #1358 from haukepetersen/fix_sam3x_vtimer

cpu - sam3x8e: fixed vtimer, added timer_set_absolute
Merge pull request #1187 from Kijewski/mbed_lpc1768-makefile-cleanup

lpc1768: cleanup Makefile
Split RPL into core and mode related functions.
drivers - gpio: expanded gpio driver interface

- added functions for en|disabling a pins interrupt
driver - gpio: small adjustments
Merge pull request #1167 from fabianbrandt/rpl_base_split

Split RPL into core and mode related functions.
applications: set stack size correctly

The correct stack size for all examples and test applications correctly.
KERNEL_CONF_STACKSIZE_MAIN is the correct stack size for any thread
using printf.

Also adapted black lists accordingly.
Merge pull request #1368 from haukepetersen/fix_gpio_disableinterrupt

drivers - gpio: expanded gpio driver interface
sys/ps: s/float/int for runtime

The high precision isn't needed, use per mille instead.
Circumvents printf problems on some platforms.

Also: prevent division by zero.