aspell: fix const definitions for llvm

Patch (thanks to kpachnis) from:

http://www.freebsd.org/cgi/query-pr.cgi?pr=180565&cat=

Closes Homebrew/homebrew#27559.
Closes Homebrew/homebrew#27411.

Formula/aspell.rb

@@ -567,6 +567,9 @@ class Aspell < Formula
     resources.map(&:name)
   end
 
+  # const problems with llvm: http://www.freebsd.org/cgi/query-pr.cgi?pr=180565&cat=
+  def patches; DATA; end
+
   def install
     system "./configure", "--prefix=#{prefix}"
     system "make install"
@@ -593,3 +596,25 @@ class Aspell < Formula
     end
   end
 end
+
+__END__
+diff --git a/interfaces/cc/aspell.h b/interfaces/cc/aspell.h
+index 9c8e81b..2cd00d4 100644
+--- a/interfaces/cc/aspell.h
++++ b/interfaces/cc/aspell.h
+@@ -237,6 +237,7 @@ void delete_aspell_can_have_error(struct AspellCanHaveError * ths);
+ /******************************** errors ********************************/
+
+
++#ifndef __cplusplus
+ extern const struct AspellErrorInfo * const aerror_other;
+ extern const struct AspellErrorInfo * const aerror_operation_not_supported;
+ extern const struct AspellErrorInfo * const   aerror_cant_copy;
+@@ -322,6 +323,7 @@ extern const struct AspellErrorInfo * const   aerror_missing_magic;
+ extern const struct AspellErrorInfo * const   aerror_bad_magic;
+ extern const struct AspellErrorInfo * const aerror_expression;
+ extern const struct AspellErrorInfo * const   aerror_invalid_expression;
++#endif
+
+
+ /******************************* speller *******************************/