[amiwm] Do another pass to clean up build warnings

This is mostly a "dangling if" cleanup, but I did add some other
comments here and there!

libami/Makefile.in

@@ -8,7 +8,7 @@ RANLIB = @RANLIB@
 CFLAGS = @CFLAGS@
 YFLAGS = -d
 DEFS = @DEFS@
-ALL_CFLAGS = -I@srcdir@ -I@top_srcdir@ $(DEFS) $(CFLAGS) @X_CFLAGS@
+ALL_CFLAGS = -Wall -I@srcdir@ -I@top_srcdir@ $(DEFS) $(CFLAGS) @X_CFLAGS@
 LIBS = @X_LIBS@ @X_PRE_LIBS@ -lXext -lXmu -lX11 @X_EXTRA_LIBS@ @LIBS@
 prefix = @prefix@
 exec_prefix = @exec_prefix@