Switch -Wnormalized=id to -Wnormalized=nfkc

Modified -Wnormalized flag to nfkc option in configure.ac to avoid source code
identifier confusion.

Fixes #24467

Signed-off-by: Fernando Fernandez Mancera <ffernandezmancera@gmail.com>

changes/ticket24467

@@ -0,0 +1,3 @@
+  o Code simplification and refactoring:
+    - Switch -Wnormalized=id to -Wnormalized=nfkc in configure.ac to avoid
+      source code identifier confusion. Closes ticket 24467.

configure.ac

@@ -2017,7 +2017,7 @@ if test "x$enable_gcc_warnings_advisory" != "xno"; then
      -Wnon-literal-null-conversion
      -Wnon-pod-varargs
      -Wnonportable-cfstrings
-     -Wnormalized=id
+     -Wnormalized=nfkc
      -Wnull-arithmetic
      -Wnull-character
      -Wnull-conversion