Port to LLVM 3.3

Major changes are:
- Switching to llvm-link to build archive files
- Use GetMallocUsage instead of GetTotalMemoryUsage (be aware of bug in
  LLVM 3.3 http://llvm.org/bugs/show_bug.cgi?id=16847)
- intrinsic library functions like memcpy/mov/set use weak linkage to be
  replaced by e.g. uclibc functions
- rewrote linking with library
- enhanced MemoryLimit test case to check if mallocs were successful
Added some of the common *at functions to the model
Fixed unused static function warning for forceImport
Fixed multiple definitions of POSIX file functions

Function like stat() were defined for 32bit and 64bit version.
Added compile time based selection of appropriate version
using GNUC macros __x86_64__ and __ppc64__.
Fixed bug where divide by zero bugs would only be detected once in a program
even if there were many divide by zero bugs.

The fix basically inlines all function calls to klee_div_zero_check()
so that each call to klee_report_error() is a unique instruction
for each instrumentation of a divide operation.

It also seems that inlining the call "magically" fixed the debug information
(file and line number) of the instruction so that the debug information on the
inlined instructions matches that of the instrumented division instruction.

Note that the command line option -emit-all-errors could be used to
workaround the bug fixed in this commit.
Implemented runtime check for overshift (controllable with --check-overshift
command line argument).

Overshift is where a Shl, AShr or LShr has a shift width greater
than the bit width of the first operand. This is undefined behaviour
in LLVM so we report this as an error.
Compile separate version of fd files only for LLVM 3.3 or higher
Merge pull request #17 from MartinNowack/LLVM33

Make KLEE compile with LLVM 2.3.
Lower intrinsic instruction "llvm.trap" to a call of the abort() function.
Replace implementation of linkWithLibrary()
Add missing header file and linker parameter
Obey --max-forks in switch statements
Merge pull request #27 from antiAgainst/intrinsic-trap

Lower intrinsic instruction "llvm.trap" to a call of the abort() function.
Merge pull request #25 from paulmar/master

Added some of the common *at functions & others to the model.  Obey --max-forks in switch statements.
Extending ./configure with support to use metaSMT.
Merge pull request #39 from hpalikareva/master

Extending ./configure with support to use metaSMT.
Merge pull request #34 from ddcc/master

Replace current implementation of linkWithLibrary()
Remove llvm.trap declaration after cleaning all uses.
Added Output/ and site.exp to .gitignore
Fixed compilation on LLVM 2.9.  irreader should be linked only for LLVM >= 3.3