When abidiff fails print out the XML diff

This can be useful for fixing the CI if needed
without the necessity to run abidw locally.

Also rename the CI job to make its purpose clearer.

Reviewed-by: Hugo Landau <hlandau@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/22689)

.github/workflows/ci.yml

@@ -264,7 +264,7 @@ jobs:
     - name: make test
       run: make test HARNESS_JOBS=${HARNESS_JOBS:-4}
 
-  fips_and_ktls:
+  full_feat_w_abidiff:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v4
@@ -287,9 +287,17 @@ jobs:
         cat /proc/cpuinfo
         ./util/opensslwrap.sh version -c
     - name: Check ABI compatibility for libcrypto
-      run: abidiff ./.github/workflows/libcrypto-abi.xml ./libcrypto.so
+      run: |
+        if ! abidiff ./.github/workflows/libcrypto-abi.xml ./libcrypto.so ; then
+          abidw --out-file libcrypto-abi-new.xml ./libcrypto.so
+          diff -u ./.github/workflows/libcrypto-abi.xml libcrypto-abi-new.xml
+        fi
     - name: Check ABI compatibility for libssl
-      run: abidiff ./.github/workflows/libssl-abi.xml ./libssl.so
+      run: |
+        if ! abidiff ./.github/workflows/libssl-abi.xml ./libssl.so ; then
+          abidw --out-file libssl-abi-new.xml ./libssl.so
+          diff -u ./.github/workflows/libssl-abi.xml libssl-abi-new.xml
+        fi
     - name: make test
       run: make test HARNESS_JOBS=${HARNESS_JOBS:-4}