remove clconfig.h.in and lib/kernel/clang.mk

- these are not referenced anywhere and seem to be unused leftovers
Initial CMake buildsystem commit

Converted most of top level configure.ac and Makefile.am into CMakeLists.txt.
Added cmake versions of config.h.in, pocl.icd.in, pocl.pc.in.
Most of LLVM & Clang related stuff is in cmake/LLVM.cmake module.

Changes against configure.ac setup:
- remove install-paths.h references (most are unused anyway); replace
  PKG*DIR variables from install-paths.h with defines from config.h
- replace PACKAGE_VERSION with POCL_VERSION
- replace CLFLAGS with KERNEL_CL_FLAGS, and CLANGXX_FLAGS with
  KERNEL_CLANGXX_FLAGS - they seem more fitting and less confusing (with
  LLVM_{CXX,C,CL}FLAGS being values from llvm-config)
- changed TARGET-{LLC,CLANG}-FLAGS into {CELL,TCE}-{LLC,CLANG}-FLAGS
  seems more consistent wrt >1 ocl "targets"
- removed {TARGET,HOST}_SIZEOF_<type> defines, they all seem unused;
  there is some code using SIZEOF_<type> defines though.

Missing stuff:
- HOST_{LLC,CLANG,...}_FLAGS setup is incomplete, especially on !x86, and
  also sanitization of various triplets is missing
- Other platforms than linux need testing, may not work
- TCE & Cell need testing
fix include paths for dev_image.h
Add CMakeLists.txt for include/*
Initial version of cmake/bitcode_rules.cmake

This is the cmake equivalent of lib/kernel/rules.mk
Initial version of lib/CMakeLists.txt

unfinished stuff: various OPENCL_* flags
Add the initial version of lib/llvmopencl/CMakeLists.txt

- needs a bit of polish on linker flags
Initial version of CMakeLists for lib/CL{/devices,}

- currently builds the entire libpocl as a single library from a list
  of sources including devices/* sources. May need to be changed to
  several libraries (like libtool "convenience" library) b/c of flags.
Initial version of CMakeLists for lib/kernel/*

- uses bitcode_rules.cmake (rules.mk) which uses
  add_custom_target and add_custom_command - quite
  clumsy but haven't found a better way to do it yet
Initial version of CMakeLists.txt for lib/poclu
Initial version of CMakeLists for scripts/*

- only handles pocl-standalone
- pocl-standalone.in.cmake needs finishing "TARGET" flags
Initial version of CMakeLists.txt for examples/*

- only handles examples/examples* for the moment; external
  testsuites aren't done yet
Initial version of CMakeLists for tests/{kernel,regression,runtime}

- most test need finishing AT_SKIP_IF, AT_FAIL_IF stuff
Initial version of examples/standalone/CMakeLists.txt

- fix a related bug in scripts/CMakeLists.txt
Initial versions of CMakeLists for examples/{trig,scalarwave}
Remove POCL_BUILDING=1 from test environment

- tests should be runnable against installed POCL as well
Initial version of tests/workgroup/CMakeLists.txt
Separate lib/CL/devices build system

- sources in devices/ are now built into their own "convenience" library
  and linked into libpocl, instead of building as part of libpocl sources.
  This makes it easier to deal with C/LD flags, and the cmakelists shorter.
Fix skip/will-fail of tests in examples/example*
Finish tests/kernel

- add a few missing tests
- better pass regexp
- add skip-if / fail-if conditions