[atk] Add missing ATK_VERSION_2_30

[Michael Catanzaro <mcatanzaro src gnome org>]

commit f1acd0aeae12ec1c15cd671a22ea28ce140d81c7
Author: Michael Catanzaro <mcatanzaro igalia com>
Date:   Tue May 15 22:33:36 2018 -0500

    Add missing ATK_VERSION_2_30
    
    /usr/include/atk-1.0/atk/atkversion.h:379:33: error: "ATK_VERSION_2_30" is not defined, evaluates to 0 
[-Werror=undef]
     #if ATK_VERSION_MIN_REQUIRED >= ATK_VERSION_2_30
                                     ^~~~~~~~~~~~~~~~
    /usr/include/atk-1.0/atk/atkversion.h:387:31: error: "ATK_VERSION_2_30" is not defined, evaluates to 0 
[-Werror=undef]
     #if ATK_VERSION_MAX_ALLOWED < ATK_VERSION_2_30
                                   ^~~~~~~~~~~~~~~~

 atk/atkversion.h.in |   10 ++++++++++
 1 files changed, 10 insertions(+), 0 deletions(-)
---
diff --git a/atk/atkversion.h.in b/atk/atkversion.h.in
index c5ec017..36946db 100644
--- a/atk/atkversion.h.in
+++ b/atk/atkversion.h.in
@@ -176,6 +176,16 @@
  */
 #define ATK_VERSION_2_14       (G_ENCODE_VERSION (2, 14))
 
+/**
+ * ATK_VERSION_2_30:
+ *
+ * A macro that evaluates to the 2.30 version of ATK, in a format
+ * that can be used by the C pre-processor.
+ *
+ * Since: 2.30
+ */
+#define ATK_VERSION_2_30       (G_ENCODE_VERSION (2, 30))
+
 /* evaluates to the current stable version; for development cycles,
  * this means the next stable target
  */