Don't #include header files in extern "C" blocks.

Now that we have template code in them, that doesn't work.

Change-Id: I9ead5d202b0d8c9b848cf25a1f247f824394a168
Reviewed-on: https://boringssl-review.googlesource.com/8733
Reviewed-by: David Benjamin <davidben@google.com>
diff --git a/include/openssl/ec.h b/include/openssl/ec.h
index 8e90ae3..124b989 100644
--- a/include/openssl/ec.h
+++ b/include/openssl/ec.h
@@ -353,9 +353,6 @@
 OPENSSL_EXPORT size_t EC_get_builtin_curves(EC_builtin_curve *out_curves,
                                             size_t max_num_curves);
 
-/* Old code expects to get EC_KEY from ec.h. */
-#include <openssl/ec_key.h>
-
 
 #if defined(__cplusplus)
 }  /* extern C */
@@ -373,6 +370,9 @@
 
 #endif
 
+/* Old code expects to get EC_KEY from ec.h. */
+#include <openssl/ec_key.h>
+
 #define EC_R_BUFFER_TOO_SMALL 100
 #define EC_R_COORDINATES_OUT_OF_RANGE 101
 #define EC_R_D2I_ECPKPARAMETERS_FAILURE 102