vim-ide-integration: -I<dir> workaround is no longer needed

Since commit ecbaf980 (-I$(dir $(3)) in
gb_CObject__command_pattern is no longer needed, 2017-11-01).

Change-Id: I9d6b7436f7b6e865d37e358adb9cf075e4e51bff

bin/gbuild-to-ide

@@ -365,10 +365,6 @@ class VimIntegrationGenerator(IdeIntegrationGenerator):
                 command += '='
                 command += value
 
-        # The directory of the file is missing from lib's include list, as that
-        # one is not the same for all source files in the lib.
-        command += ' -I' + os.path.dirname(file)
-
         for include in lib.include:
             command += ' -I'
             command += include