Update comment to reflect Swift version bump. NFC

Author: tkremenek

test/IRGen/objc.swift

@@ -146,6 +146,6 @@ class WeakObjC {
 // CHECK:  i32 1, !"Objective-C Image Info Version", i32 0}
 // CHECK:  i32 1, !"Objective-C Image Info Section", !"__DATA,__objc_imageinfo,regular,no_dead_strip"}
 //   84346624 == (5 << 24) | (7 << 16) | (7 << 8).
-//     5 and 6 is the current major.minor version. 7 is the Swift ABI version.
+//     5 and 7 is the current major.minor version. 7 is the Swift ABI version.
 // CHECK:  i32 4, !"Objective-C Garbage Collection", i32 84346624}
 // CHECK:  i32 1, !"Swift Version", i32 7}