Set version info with #define

Don't use `#cmakedefine` to define values that can be zero.
`#cmakedefine` only sets the definition when the corresponding value in
CMake itself has a truthy value. `0` has a false-y value, so
SWIFT_VERSION_MINOR is undefined for 6.0 resulting in some things
breaking.

Author: etcwilde

include/swift/Runtime/CMakeConfig.h.in

@@ -7,7 +7,7 @@
 #cmakedefine01 SWIFT_BNI_OS_BUILD
 #cmakedefine01 SWIFT_BNI_XCODE_BUILD
 
-#cmakedefine SWIFT_VERSION_MAJOR "@SWIFT_VERSION_MAJOR@"
-#cmakedefine SWIFT_VERSION_MINOR "@SWIFT_VERSION_MINOR@"
+#define SWIFT_VERSION_MAJOR "@SWIFT_VERSION_MAJOR@"
+#define SWIFT_VERSION_MINOR "@SWIFT_VERSION_MINOR@"
 
 #endif