[Ada] Work around CodePeer bug by declaring variable

[Pierre-Marie de Rodat]

This commit works around a CodePeer bug where CodePeer thinks
Get_32_Bit_Val returns something uninitialized.

Tested on x86_64-pc-linux-gnu, committed on trunk

gcc/ada/

        * atree.adb (Get_32_Bit_Field): Declare result before returning.
diff --git a/gcc/ada/atree.adb b/gcc/ada/atree.adb
--- a/gcc/ada/atree.adb
+++ b/gcc/ada/atree.adb
@@ -513,8 +513,13 @@ package body Atree is
 
          function Cast is new
            Unchecked_Conversion (Field_Size_32_Bit, Field_Type);
+
+         Result : constant Field_Type := Cast (Get_32_Bit_Val (N, Offset));
+         --  Note: declaring Result here instead of directly returning
+         --  Cast (...) helps CodePeer understand that there are no issues
+         --  around uninitialized variables.
       begin
-         return Cast (Get_32_Bit_Val (N, Offset));
+         return Result;
       end Get_32_Bit_Field;
 
       function Get_32_Bit_Field_With_Default