[cmake] `cmakeBuild()` does not work when passed a variable with a hyphen

The assert in `cmakeBuild()` allows for variable names with a hyphen, and so does cmake.
But variables in bash cannot contain a hyphen, however `cmakeBuild()` uses bash variables to generate the final arguments to pass to cmake. \
This results in an error like this:
```
/home/.../bin/bash: line 7: cmake_type_SPIRV-Headers_SOURCE_DIR: invalid variable name
```