scanner: Fix broken private-code generation

Missing a closing bracket.

Reviewed-by: Daniel Stone <daniels@collabora.com>

src/scanner.c

diff --git a/src/scanner.c b/src/scanner.c
index c93070c..1737911 100644
--- a/src/scanner.c
+++ b/src/scanner.c
@@ -1748,7 +1748,7 @@
 		       "# define __has_attribute(x) 0  /* Compatibility with non-clang compilers. */\n"
 		       "#endif\n\n");
 
-		printf("#if (__has_attribute(visibility) || defined(__GNUC__) && __GNUC__ >= 4\n"
+		printf("#if (__has_attribute(visibility) || defined(__GNUC__) && __GNUC__ >= 4)\n"
 		       "#define WL_PRIVATE __attribute__ ((visibility(\"hidden\")))\n"
 		       "#else\n"
 		       "#define WL_PRIVATE\n"