CI: Fix mingw cmake build

.gitlab-ci.yml

@@ -182,6 +182,7 @@ cmake:linux:clang:static:
     - win32-ps
   variables:
     CHERE_INVOKING: "yes"
+    CC: gcc
   before_script:
     - $Env:Path="C:\msys64\usr\bin;$Env:Path"
     - bash -lc 'sh .gitlab-ci/setup_mingw.sh cmake ninja'

.gitlab-ci/setup_mingw.sh

@@ -6,7 +6,7 @@ prefix=
 if [ -n "$MINGW_PACKAGE_PREFIX" ]; then
     prefix="${MINGW_PACKAGE_PREFIX}-"
 fi
-for module in docbook-xsl doxygen libiconv python xsltproc xz zlib "$@"; do
+for module in gcc docbook-xsl doxygen libiconv python xsltproc xz zlib "$@"; do
     pacman --noconfirm -S --needed ${prefix}$module
 done