Stop ignoring updates to GCC nor to osslsigncode

The issues with GCC have been resolved:

- The bug in GCC v8.x was fixed that prevented
  `-fstack-protector-strong` to produce valid code:

  https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86832

- The issues were resolved in Git for Windows' source code that
  triggered build warnings with GCC v8.x (warnings that cause build
  failures with `DEVELOPER=1`):

  git-for-windows/git#2149

- The issue preventing Git for Windows to be compiled with GCC v9.x
  under `DEVELOPER=1` was resolved:

  git-for-windows/git#2258

- The issues preventing Git's `master` to be compiled with GCC v9.x
  (rolling up the fixes for GCC v8.x) were resolved:

  gitgitgadget/git#265

The issue with osslsigncode no longer signing the code after the upgrade
to OpenSSL v1.1.1, but pretending to succeed, has been fixed some time
recently through a rebuild of mingw-w64-osslsigncode.

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

etc/pacman.conf

@@ -22,7 +22,7 @@ HoldPkg      = pacman
 Architecture = auto
 
 # Pacman won't upgrade packages listed in IgnorePkg and members of IgnoreGroup
-IgnorePkg   = mingw-w64-i686-gcc mingw-w64-i686-gcc-libs mingw-w64-i686-osslsigncode
+#IgnorePkg   =
 #IgnoreGroup =
 
 #NoUpgrade   =