common: add NVML magic file

- create NVML magic script for file(1) command
- install NVML magic script with rpm and dpkg packages
vmem: do not unlock ctl_mtx mutex twice

The ctl_mtx mutex is unlocked at src/jemalloc/src/ctl.c:785.
common: prevent compilation for 32-bit platforms

32/64-bit detection added to makefile.
Compilation stops with a clear error message, if user attempts to
build NVML for 32-bit.
Merge pull request #47 from ldorau/vmem-fix-ctl_mtx-mutex

vmem: do not unlock ctl_mtx mutex twice
Merge pull request #48 from plebioda/nvml-magic-file

common: add NVML magic file
Merge pull request #49 from krzycz/common-prevent_32bit_compilation

common: prevent compilation for 32-bit platforms