libgbinder: update to 1.1.50.

[Rutpiv]

Testing the changes

• I tested the changes in this PR: briefly

Local build testing

• I built this PR locally for my native architecture (x86_64)
• I built this PR locally for these architectures using specific masterdirs:
  • x86_64-musl
  • i686
• I built this PR locally for these architectures (crossbuilds):
  • aarch64
  • aarch64-musl
  • armv7l
  • armv7l-musl
  • armv6l
  • armv6l-musl

---

Drops bison and flex from hostmakedepends. They are unused: the only lexer/parser (cmdline.l/cmdline.y) lives under test/binder-call, which is built by neither the release pkgconfig build target nor the make -C unit test check target. A local build confirms only pkg-config is pulled in as a host dependency.