appveyor: guard against crash-build with VS2008

The combination of `-DDEBUGBUILD`, a shared `curl.exe`, and the VS2008
compiler creates a `curl.exe` segfaulting on startup:

```
+ _bld/src/curl.exe --version
./appveyor.sh: line 122:   793 Segmentation fault      "${curl}" --version
Command exited with code 139
```
Ref: https://ci.appveyor.com/project/curlorg/curl/builds/49817266/job/651iy6qn1e238pqj#L191

Add job that triggers the issue and add the necessary logic to skip
running the affected `curl.exe`.

Ref: #13592
Closes #13654

appveyor.sh

@@ -42,8 +42,11 @@ if [ "${BUILD_SYSTEM}" = 'CMake' ]; then
   [ "${PRJ_CFG}" = 'Debug' ] && options+=' -DCMAKE_RUNTIME_OUTPUT_DIRECTORY_DEBUG='
   [ "${PRJ_CFG}" = 'Release' ] && options+=' -DCMAKE_RUNTIME_OUTPUT_DIRECTORY_RELEASE='
   [[ "${PRJ_GEN}" = *'Visual Studio'* ]] && options+=' -DCMAKE_VS_GLOBALS=TrackFileAccess=false'
-  # Fails to run without this run due to missing MSVCR90.dll
-  [ "${PRJ_GEN}" = 'Visual Studio 9 2008' ] && options+=' -DCURL_STATIC_CRT=ON'
+  if [ "${PRJ_GEN}" = 'Visual Studio 9 2008' ]; then
+    [ "${PRJ_CFG}" = 'Debug' ] && [ "${DEBUG}" = 'ON' ] && [ "${SHARED}" = 'ON' ] && SKIP_RUN='Crash on startup in -DDEBUGBUILD shared builds'
+    # Fails to run without this due to missing MSVCR90.dll / MSVCR90D.dll
+    options+=' -DCURL_STATIC_CRT=ON'
+  fi
   # shellcheck disable=SC2086
   cmake -B _bld "-G${PRJ_GEN}" ${TARGET:-} ${options} \
     "-DCURL_USE_OPENSSL=${OPENSSL}" \

appveyor.yml

@@ -48,6 +48,17 @@ environment:
       SHARED: 'ON'
       TESTING: 'OFF'
       DISABLED_TESTS: ''
+    - job_name: 'CMake, VS2008, Debug, x86, Schannel, Build-only'
+      APPVEYOR_BUILD_WORKER_IMAGE: 'Visual Studio 2015'
+      BUILD_SYSTEM: CMake
+      PRJ_GEN: 'Visual Studio 9 2008'
+      PRJ_CFG: Debug
+      SCHANNEL: 'ON'
+      ENABLE_UNICODE: 'OFF'
+      HTTP_ONLY: 'OFF'
+      SHARED: 'ON'
+      TESTING: 'OFF'
+      DISABLED_TESTS: ''
     - job_name: 'CMake, VS2022, Release, x64, OpenSSL 3.2, WebSockets, Build-only'
       APPVEYOR_BUILD_WORKER_IMAGE: 'Visual Studio 2022'
       BUILD_SYSTEM: CMake