archivers/gcab: update to 1.5

New Features:

• New gcab_file_set_bytes() API (!8)
• meson: Register the gcab executable with meson (!10)

Bugfixes:

• Fixed MSZIP compression when deflate algorithm would expand (#16)
  
  Previous versions of gcab can produce "incorrect" archives (when a compressed block is larger than its input). They are however supported by gcab itself, and we will keep support for it for the foreseeble future.
• gcab: avoid runtime warnings (!7)
• Fix coverity warnings (!9)