Add CPack configuration for debian packages

Allows to automatically generate .deb based on current generated `install`
target. Some of package settings are taken from exiting CMake variables, some
from host system.
Fix ArrayLiteralExp for boolean arrays.

GitHub: Fixes #602.
Merge pull request #603 from klickverbot/bool-array

Fix ArrayLiteralExp for boolean arrays.
Merge pull request #580 from Dicebot/deb-package

Add CPack configuration for debian packages
Fix dmd test template2962 by removing nestedVars.

nestedVars was always a copy of closureVars. There was no point to it
existing.
Merge pull request #618 from ckamm/fix-nestedvars

Fix dmd test template2962 by removing nestedVars.
Make intrinsic parameter errors in CallExp::toElem() fatal.

Returning null will crash just about any other glue layer code.

Ideally, we'd catch those during semantic analysis (glue layer
errors are always to be avoided due to speculative compilation),
but this at least avoids the segfaults.
Reject non-integer atomic load/store during codegen.

This avoids hitting an LLVM assert during codegen.
Fix atomic{Load, Store}() for struct types.

GitHub: Fixes #616.
Merge pull request #619 from klickverbot/core-atomic-struct

Fix atomic{Load, Store}() for struct types.
Add alternative llvm-config names.

FreeBSD/PC-BSD has a different naming scheme for multiple LLVM
installations.