appveyor: Update MinGW packages recursively
appveyor: Update MinGW packages recursively

Previously, newer versions of the C-runtime library and Windows API
headers weren't getting installed.

TamirEvan/mupdf,TamirEvan/mupdf,TamirEvan/mupdf,TamirEvan/mupdf,TamirEvan/mupdf,TamirEvan/mupdf,TamirEvan/mupdf,TamirEvan/mupdf