build/windows: Make deps install "modular"

Since almost the same code is used in the 3 stages, let's reuse it.

build/windows/gitlab-ci/1_build-deps-msys2.sh

@@ -52,6 +52,7 @@ if [ $retry -eq 0 ]; then
   echo "MSYS2 pacman repeatedly failed. See: https://github.com/msys2/MSYS2-packages/issues/4340"
   exit 1
 fi
+# End of install
 
 
 # Clone babl and GEGL (follow master branch)

build/windows/gitlab-ci/2_build-gimp-msys2.sh

@@ -40,25 +40,9 @@ fi
 
 
 # Install the required (pre-built) packages for GIMP
-export DEPS_PATH="build/windows/gitlab-ci/all-deps-uni.txt"
-sed -i "s/DEPS_ARCH_/${MINGW_PACKAGE_PREFIX}-/g" $DEPS_PATH
-export GIMP_DEPS=`cat $DEPS_PATH`
-
-retry=3
-while [ $retry -gt 0 ]; do
-  timeout --signal=KILL 3m pacman --noconfirm -S --needed base-devel                         \
-                                                          ${MINGW_PACKAGE_PREFIX}-toolchain  \
-                                                          $GIMP_DEPS && break
-  echo "MSYS2 pacman timed out. Trying again."
-  taskkill //t //F //IM "pacman.exe"
-  rm -f c:/msys64/var/lib/pacman/db.lck
-  : $((--retry))
-done
-
-if [ $retry -eq 0 ]; then
-  echo "MSYS2 pacman repeatedly failed. See: https://github.com/msys2/MSYS2-packages/issues/4340"
-  exit 1
-fi
+DEPS_CODE=$(cat build/windows/gitlab-ci/1_build-deps-msys2.sh)
+DEPS_CODE=$(sed -n '/# Install the/,/# End of install/p' <<< $DEPS_CODE)
+echo "$DEPS_CODE" | bash
 
 # Install QOI header manually
 # mingw32 package of qoi was removed from MSYS2, we have download it by ourselves

build/windows/gitlab-ci/3_package-gimp-uni_base.sh

@@ -25,24 +25,9 @@ fi
 
 if [[ "$BUILD_TYPE" != "CI_CROSS" ]]; then
   # Install the required (pre-built) packages again
-  export DEPS_PATH="build/windows/gitlab-ci/all-deps-uni.txt"
-  sed -i "s/DEPS_ARCH_/${MINGW_PACKAGE_PREFIX}-/g" $DEPS_PATH
-  export GIMP_DEPS=`cat $DEPS_PATH`
-  retry=3
-  while [ $retry -gt 0 ]; do
-    timeout --signal=KILL 3m pacman --noconfirm -S --needed base-devel                         \
-                                                            ${MINGW_PACKAGE_PREFIX}-toolchain  \
-                                                            $GIMP_DEPS && break
-    echo "MSYS2 pacman timed out. Trying again."
-    taskkill //t //F //IM "pacman.exe"
-    rm -f c:/msys64/var/lib/pacman/db.lck
-    : $((--retry))
-  done
-
-  if [ $retry -eq 0 ]; then
-    echo "MSYS2 pacman repeatedly failed. See: https://github.com/msys2/MSYS2-packages/issues/4340"
-    exit 1
-  fi
+  DEPS_CODE=$(cat build/windows/gitlab-ci/1_build-deps-msys2.sh)
+  DEPS_CODE=$(sed -n '/# Install the/,/# End of install/p' <<< $DEPS_CODE)
+  echo "$DEPS_CODE" | bash
 fi