ci-artifacts: ask please.sh for the UCRT64 flavor explicitly

Now that build-extra has learned to accept `--architecture=ucrt64` in
`create_sdk_artifact`, point both invocations at it. Without the flag,
please.sh's auto-detect picks `x86_64`, hard-maps that to MINGW64 /
/mingw64/, and writes a broken artifact (no /mingw64/bin exists on this
branch, the Pacman package set carries the wrong prefix).

This results in MSYSTEM=UCRT64 and PATH starting with /ucrt64/bin, as is
needed for the artifact's own /etc/profile to be correct out of the box.
For that reason, we now also verify that _that_ GCC is found ;-)

Assisted-by: Opus 4.7
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Author: dscho

.github/workflows/ci-artifacts.yml

@@ -34,7 +34,7 @@ jobs:
       - name: build git-sdk-64-minimal-sdk
         shell: bash
         run: |
-          sh -x ./build-extra/please.sh create-sdk-artifact --sdk=git-sdk-64.git minimal-sdk &&
+          sh -x ./build-extra/please.sh create-sdk-artifact --architecture=ucrt64 --sdk=git-sdk-64.git minimal-sdk &&
           cygpath -aw minimal-sdk/usr/bin >>$GITHUB_PATH
       - name: compress artifact
         shell: bash
@@ -52,7 +52,7 @@ jobs:
           set -x
           . /etc/profile
           test "$(cygpath -aw /)" = "${{github.workspace}}\minimal-sdk" || exit 1
-          test "$(type -p gcc)" = "/mingw64/bin/gcc" || exit 1
+          test "$(type -p gcc)" = "/ucrt64/bin/gcc" || exit 1
           make -C ../git DEVELOPER=1 NO_PERL=1 NO_RUST=UnfortunatelyYes SKIP_DASHED_BUILT_INS=YesPlease -j8 all strip
       - name: compress git artifacts
         shell: bash
@@ -105,7 +105,7 @@ jobs:
         run: git clone --depth=1 --single-branch -b main https://github.com/git-for-windows/build-extra
       - name: build git-sdk-64-build-installers
         shell: bash
-        run: sh -x ./build-extra/please.sh create-sdk-artifact --sdk=git-sdk-64.git build-installers
+        run: sh -x ./build-extra/please.sh create-sdk-artifact --architecture=ucrt64 --sdk=git-sdk-64.git build-installers
       - name: compress artifact
         shell: bash
         run: |

.github/workflows/test-ci-artifacts.yml

@@ -87,7 +87,7 @@ jobs:
           test "$(cygpath -aw /)" = "${{github.workspace}}\minimal-sdk" || exit 1
 
           # comes with GCC and can compile a DLL
-          test "$(type -p gcc)" = "/mingw64/bin/gcc" || exit 1
+          test "$(type -p gcc)" = "/ucrt64/bin/gcc" || exit 1
           cat >dll.c <<-\EOF &&
           __attribute__((dllexport)) int increment(int i)
           {