1) I came across another review with the same license question. The source files have one of the GPLv2, GPLv2+ and LGPLv2+ headers each. They get compiled and produce 1 final binary executable. None of the headers (or other source code files) go to the final RPM.
What goes to the license tag of the package?
Ref: https://bugzilla.redhat.com/show_bug.cgi?id=537325#c4
2) Hypothetical question (although happens rather frequently): What if there was a -devel subpackage and .h files with different licenses ended up in this -devel subpackage?
Orcan