Add option USE_BUNDLED_BUSTED to third-party

- When not running the unit tests, building the third-party busted,
  nvim-client and other dependencies can be skipped by passing
  -DUSE_BUNDLED_BUSTED=FALSE to the third-party project.

third-party/cmake/BuildLuarocks.cmake

@@ -1,3 +1,5 @@
+option(USE_BUNDLED_BUSTED "Use the bundled version of busted to run tests." ON)
+
 if(USE_BUNDLED_LUAJIT)
   list(APPEND LUAROCKS_OPTS
     --with-lua=${DEPS_INSTALL_DIR}
@@ -28,6 +30,30 @@ if(USE_BUNDLED_LUAJIT)
   add_dependencies(luarocks luajit)
 endif()
 
+# Each target depends on the previous module, this serializes all calls to
+# luarocks since it is unhappy to be called in parallel.
+add_custom_command(OUTPUT ${DEPS_LIB_DIR}/luarocks/rocks/lua-messagepack
+  COMMAND ${DEPS_BIN_DIR}/luarocks
+  ARGS build lua-messagepack CC=${DEPS_C_COMPILER} LD=${DEPS_C_COMPILER}
+  DEPENDS luarocks)
+add_custom_target(lua-messagepack
+  DEPENDS ${DEPS_LIB_DIR}/luarocks/rocks/lua-messagepack)
+
+# Like before, depend on lua-messagepack to ensure serialization of install
+# commands
+add_custom_command(OUTPUT ${DEPS_LIB_DIR}/luarocks/rocks/lpeg
+  COMMAND ${DEPS_BIN_DIR}/luarocks
+  ARGS build lpeg CC=${DEPS_C_COMPILER} LD=${DEPS_C_COMPILER}
+  DEPENDS lua-messagepack)
+add_custom_target(lpeg
+  DEPENDS ${DEPS_LIB_DIR}/luarocks/rocks/lpeg)
+
+list(APPEND THIRD_PARTY_DEPS lua-messagepack lpeg)
+
+if(USE_BUNDLED_BUSTED)
+  # The following are only required if we want to run tests
+  # with busted
+  
   add_custom_command(OUTPUT ${DEPS_LIB_DIR}/luarocks/rocks/stable-busted-deps
     COMMAND ${DEPS_BIN_DIR}/luarocks
     ARGS build lua_cliargs 2.3-3 CC=${DEPS_C_COMPILER} LD=${DEPS_C_COMPILER}
@@ -50,7 +76,7 @@ add_custom_command(OUTPUT ${DEPS_LIB_DIR}/luarocks/rocks/stable-busted-deps
     COMMAND ${DEPS_BIN_DIR}/luarocks
     ARGS build xml 1.1.1-1 CC=${DEPS_C_COMPILER} LD=${DEPS_C_COMPILER}
     COMMAND touch ${DEPS_LIB_DIR}/luarocks/rocks/stable-busted-deps
-  DEPENDS luarocks)
+    DEPENDS lpeg)
   add_custom_target(stable-busted-deps
     DEPENDS ${DEPS_LIB_DIR}/luarocks/rocks/stable-busted-deps)
   
@@ -61,30 +87,12 @@ add_custom_command(OUTPUT ${DEPS_BIN_DIR}/busted
   add_custom_target(busted
     DEPENDS ${DEPS_BIN_DIR}/busted)
   
-# lua-messagepack doesn't depend on busted, but luarocks is unhappy to have
-# two instances running in parallel.  So we depend on busted to force it to
-# be serialized.
-add_custom_command(OUTPUT ${DEPS_LIB_DIR}/luarocks/rocks/lua-messagepack
-  COMMAND ${DEPS_BIN_DIR}/luarocks
-  ARGS build lua-messagepack CC=${DEPS_C_COMPILER} LD=${DEPS_C_COMPILER}
-  DEPENDS busted)
-add_custom_target(lua-messagepack
-  DEPENDS ${DEPS_LIB_DIR}/luarocks/rocks/lua-messagepack)
-
-# Like before, depend on lua-messagepack to ensure serialization of install
-# commands
-add_custom_command(OUTPUT ${DEPS_LIB_DIR}/luarocks/rocks/lpeg
-  COMMAND ${DEPS_BIN_DIR}/luarocks
-  ARGS build lpeg CC=${DEPS_C_COMPILER} LD=${DEPS_C_COMPILER}
-  DEPENDS lua-messagepack)
-add_custom_target(lpeg
-  DEPENDS ${DEPS_LIB_DIR}/luarocks/rocks/lpeg)
-
   add_custom_command(OUTPUT ${DEPS_LIB_DIR}/luarocks/rocks/nvim-client
     COMMAND ${DEPS_BIN_DIR}/luarocks
     ARGS build https://raw.githubusercontent.com/neovim/lua-client/8cc5b6090ac61cd0bba53ba984f15792fbb64573/nvim-client-0.0.1-11.rockspec CC=${DEPS_C_COMPILER} LD=${DEPS_C_COMPILER} LIBUV_DIR=${DEPS_INSTALL_DIR}
-  DEPENDS lpeg libuv)
+    DEPENDS busted libuv)
   add_custom_target(nvim-client
     DEPENDS ${DEPS_LIB_DIR}/luarocks/rocks/nvim-client)
   
-list(APPEND THIRD_PARTY_DEPS stable-busted-deps busted lua-messagepack lpeg nvim-client)
+  list(APPEND THIRD_PARTY_DEPS stable-busted-deps busted nvim-client)
+endif()