Allow hints for z3

Former-commit-id: 24885ab1bc

CMakeLists.txt

@@ -27,7 +27,8 @@ option(STORM_USE_INTELTBB "Sets whether the Intel TBB libraries should be used."
 option(STORM_USE_COTIRE "Sets whether Cotire should be used (for building precompiled headers)." OFF)
 option(LINK_LIBCXXABI "Sets whether libc++abi should be linked." OFF)
 option(USE_LIBCXX "Sets whether the standard library is libc++." OFF)
-set(GUROBI_ROOT "" CACHE STRING "The root directory of Gurobi (if available).")
+set(GUROBI_ROOT "" CACHE STRING "A hint to the root directory of Gurobi (optional).")
+set(Z3_ROOT "" CACHE STRING "A hint to the root directory of Z3 (optional).")
 set(CUDA_ROOT "" CACHE STRING "The root directory of CUDA.")
 set(MSAT_ROOT "" CACHE STRING "The root directory of MathSAT (if available).")
 set(ADDITIONAL_INCLUDE_DIRS "" CACHE STRING "Additional directories added to the include directories.")