Merge: Replace z3_get_error_msg_ex with z3_get_error_msg

Fixes IagoAbal#20.

The z3_get_error_msg_ex function was removed from the Z3 C API for version 4.8.5 of Z3, which caused a linker error. This removes the references to z3_get_error_msg_ex and replaces them with z3_get_error_msg to fix that linker error.

Author: IagoAbal

src/Z3/Base.hs

@@ -2498,7 +2498,7 @@ z3Error cd = throw . Z3Error cd
 checkError :: Ptr Z3_context -> IO a -> IO a
 checkError cPtr m = do
   m <* (z3_get_error_code cPtr >>= throwZ3Exn)
-  where getErrStr i  = peekCString =<< z3_get_error_msg_ex cPtr i
+  where getErrStr i  = peekCString =<< z3_get_error_msg i
         throwZ3Exn i = when (i /= z3_ok) $ getErrStr i >>= z3Error (toZ3Error i)
 
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src/Z3/Base/C.hsc

@@ -1453,10 +1453,6 @@ foreign import ccall unsafe "Z3_set_error"
 foreign import ccall unsafe "Z3_get_error_msg"
     z3_get_error_msg :: Z3_error_code -> IO Z3_string
 
--- | Reference: <http://z3prover.github.io/api/html/group__capi.html#gae0aba52b5738b2ea78e0d6ad67ef1f92>
-foreign import ccall unsafe "Z3_get_error_msg_ex"
-    z3_get_error_msg_ex :: Ptr Z3_context -> Z3_error_code -> IO Z3_string
-
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 -- * Miscellaneous