Update global gitignore file and add gitignore files for every target
Switch to using system available clang and update the supported clang version to 3.5
Update btrace.pro to be able to build both 32-bit and 64-bit versions of the library

Change sw-btrace-to-compiledb to look at the end of the argv[0] rather that compare it directly to the supported drivers to account for cross-compile drivers

Update sw-btrace wrapper script to use '' and let ld.so handle finding the correct place of the library
Remove libexec dir and place all binaries into the lib dir
Fix destination path for library