[lldb] Reinstate lldb-sbapi-dwarf-enums target (NFC) (llvm#91390)

Alex pointed out in llvm#91254 that we only need the custom target if we had
more than one target depending on it. This isn't the case upstream, but
on our downstream fork, we have a second dependency. Reintroduce the
target so that everything can depend on that, without the
single-dependency foot-gun.

(cherry picked from commit dad1109)

Author: JDevlieghere

lldb/source/API/CMakeLists.txt

@@ -30,7 +30,7 @@ if(LLDB_ENABLE_LUA)
   set(lldb_lua_wrapper ${lua_bindings_dir}/LLDBWrapLua.cpp)
 endif()
 
-# Target to generate SBLanguages.h from Dwarf.def.
+# Generate SBLanguages.h from Dwarf.def.
 set(sb_languages_file
   ${CMAKE_CURRENT_BINARY_DIR}/../../include/lldb/API/SBLanguages.h)
 add_custom_command(
@@ -43,6 +43,8 @@ add_custom_command(
   DEPENDS ${LLVM_MAIN_INCLUDE_DIR}/llvm/BinaryFormat/Dwarf.def
   WORKING_DIRECTORY ${LLVM_LIBRARY_OUTPUT_INTDIR}
 )
+add_custom_target(lldb-sbapi-dwarf-enums
+  DEPENDS ${sb_languages_file})
 
 add_lldb_library(liblldb SHARED ${option_framework}
   SBAddress.cpp
@@ -121,7 +123,9 @@ add_lldb_library(liblldb SHARED ${option_framework}
   SystemInitializerFull.cpp
   ${lldb_python_wrapper}
   ${lldb_lua_wrapper}
-  ${sb_languages_file}
+
+  DEPENDS
+    lldb-sbapi-dwarf-enums
 
   LINK_LIBS
     lldbBreakpoint