codegen: Handle opaque types in c99 preamble

Author: wence-

loopy/target/c/__init__.py

@@ -80,9 +80,10 @@ def dtype_to_ctype(self, dtype):
 # {{{ preamble generator
 
 def c99_preamble_generator(preamble_info):
+    from loopy.types import to_loopy_type
     if any(dtype.is_integral() for dtype in preamble_info.seen_dtypes):
         yield("10_stdint", "#include <stdint.h>")
-    if any(dtype.numpy_dtype == np.dtype("bool")
+    if any(dtype == to_loopy_type(np.dtype("bool"))
            for dtype in preamble_info.seen_dtypes):
         yield("10_stdbool", "#include <stdbool.h>")
     if any(dtype.is_complex() for dtype in preamble_info.seen_dtypes):