Describe the bug
Linking a consumer project against the generated CMake imported targets fails on Windows/MSVC due to missing symbols.

System
Which OS, compiler, and compiler version are you using:

• OS: Windows
• Compiler and version: Visual C++

To reproduce
Issue very well described here: #1450
and also happening here: conan-io/conan-center-index#11912

External projects that link against the generated CMake imported targets, now need to define BENCHMARK_STATIC_DEFINE on their end. I think this effectively means that users on Windows would have to define that on their side when updating to 1.7.0.

This gives me the impression that this could be a "public" compile definition that is propagated transitively to consumers, such that they do not have to define this on their end. I believe introduced here: https://github.com/google/benchmark/pull/1435/files.

I would venture a guess that prior to this change, the value was already set in the generated file.

I'm happy to open a pull request to address it, just want to make sure it would not negatively impact other platforms.