Darwin: Fix wrong quoting on an error string (PR93860).

The quotes should surround all of the literal content from the pragma
that has incorrect usage.

2020-02-21  Iain Sandoe  <iain@sandoe.co.uk>

PR target/93860
* config/darwin-c.c (pop_field_alignment): Adjust quoting of
error string.

gcc/ChangeLog

+2020-02-21  Iain Sandoe  <iain@sandoe.co.uk>
+
+	PR target/93860
+	* config/darwin-c.c (pop_field_alignment): Adjust quoting of
+	error string.
+
 2020-02-21  Mihail Ionescu  <mihail.ionescu@arm.com>
 
 	* doc/sourcebuild.texi (arm_v8_1m_mve_ok):

gcc/config/darwin-c.c

@@ -79,7 +79,7 @@ pop_field_alignment (void)
       free (entry);
     }
   else
-    error ("too many %<#pragma options%> align=reset");
+    error ("too many %<#pragma options align=reset%>");
 }
 
 /* Handlers for Darwin-specific pragmas.  */