libretro: rename the core target to armsx2

CORENAME was still yaps2, so the libretro buildbot looked for
yaps2_libretro.so while CMake's OUTPUT_NAME already emitted
armsx2_libretro.so -- the artifact would not have been picked up. The
make-target alias was stale for the same reason.

The shipped armsx2_libretro.info was already correct; RetroArch pairs .so to
.info by filename stem, so the core now has its metadata.

The core has never been published, so nothing downstream breaks on the rename.

.gitlab-ci.yml

@@ -1,6 +1,6 @@
 # DESCRIPTION: GitLab CI/CD for libRetro (NOT FOR GitLab-proper)
 #
-# Builds yaps2_libretro.so on the libretro buildbot (git.libretro.com mirror)
+# Builds armsx2_libretro.so on the libretro buildbot (git.libretro.com mirror)
 # for Linux x86_64 and aarch64. Inert on GitHub — the GitHub Actions
 # workflows under .github/workflows/ are the project's own CI.
 #
@@ -17,7 +17,7 @@
 .core-defs:
   variables:
     GIT_SUBMODULE_STRATEGY: recursive
-    CORENAME: yaps2
+    CORENAME: armsx2
     # The core is emitted in the pcsx2-libretro/ subdirectory of the build
     # tree; the ci-templates pick it up from $BUILD_DIR/$EXTRA_PATH/.
     EXTRA_PATH: pcsx2-libretro

pcsx2-libretro/CMakeLists.txt

@@ -43,5 +43,5 @@ endif()
 
 # The libretro buildbot's ci-templates build the target named
 # <CORENAME>_libretro (see .gitlab-ci.yml).
-add_custom_target(yaps2_libretro)
-add_dependencies(yaps2_libretro pcsx2-libretro)
+add_custom_target(armsx2_libretro)
+add_dependencies(armsx2_libretro pcsx2-libretro)