CMake Option Names

[agurfinkel]

Unify all top-level option name. Options related to crab-llvm should start with CLAM, options related to crab should start with CRAB. Options in crab-llvm that relate on how clam configures crab should start with CLAM_CRAB_.

For example,
USE_COTIRE --> CLAM_USE_COTIRE
BUILD_CRABLLVM_LIBS_SHARED --> 'CLAM_SHARED_LIBS ALL_CRAB_DOMAINS-->CLAM_CRAB_ENABLE_ALL_DOMAINS ENABLE_CRAB_INTER-->CLAM_CRAB_ENABLE_INTERPROC CRABLLVM_STATIC_EXE-->CLAM_STATIC_EXE`