Search RzAnalysisOp.analysis_vals[] for xrefs.

[Rot127]

Your checklist for this pull request

• I've read the guidelines for contributing to this repository
• I made sure to follow the project's coding style
• I've documented or updated the documentation of every function and struct this PR changes. If not so I've explained why.
• I've added tests that prove my fix is effective or that my feature works (if possible)
• I've updated the rizin book with the relevant information (if needed)

Detailed description

The function rz_core_analysis_search_xrefs does not search through the RzAnalysisOp.anlysis_vals[] array, which was added in #1614.

In this PR a simple loop is added which searches each value for references.

Test plan

Test case was added: The memw(R17+#0x0) = ##0x1c instruction has the 0x1c value stored in RzAnalysisOp.analysis_vals[0].

Closing issues

None