CI: Test builds with TSD stubs and TLS variables

Add builds to the CI script that use the TSD dispatch stubs, but use the
TLS variable in u_current_tls.c for the dispatch table.

That's the combination you'd get with musl or other non-glibc systems.

.gitlab-ci.yml

@@ -86,6 +86,12 @@ build-x86_64-tsd-meson:
   variables:
     CONFIGURE_OPTIONS: -Dtls=false
 
+build-x86_64-tsd-tls-meson:
+  extends:
+    - .build-check-meson
+  variables:
+    CONFIGURE_OPTIONS: -Ddispatch-tls=false
+
 build-i386-tsd:
   extends:
     - .build-check-at
@@ -98,6 +104,12 @@ build-i386-tsd-meson:
   variables:
     CONFIGURE_OPTIONS: -Dtls=false --cross-file .gitlab-ci/i686-linux-gnu
 
+build-i386-tsd-tls-meson:
+  extends:
+    - .build-check-meson
+  variables:
+    CONFIGURE_OPTIONS: -Ddispatch-tls=false --cross-file .gitlab-ci/i686-linux-gnu
+
 build-pure-c-tls:
   extends:
     - .build-check-at