Remove useless duplicate inclusions of system header files.

c.h #includes a number of core libc header files, such as <stdio.h>.
There's no point in re-including these after having read postgres.h,
postgres_fe.h, or c.h; so remove code that did so.

While at it, also fix some places that were ignoring our standard pattern
of "include postgres[_fe].h, then system header files, then other Postgres
header files".  While there's not any great magic in doing it that way
rather than system headers last, it's silly to have just a few files
deviating from the general pattern.  (But I didn't attempt to enforce this
globally, only in files I was touching anyway.)

I'd be the first to say that this is mostly compulsive neatnik-ism,
but over time it might save enough compile cycles to be useful.

contrib/fuzzystrmatch/dmetaphone.c

@@ -93,9 +93,6 @@ The remaining code is authored by Andrew Dunstan <amdunstan@ncshp.org> and
 ***********************************************************************/
 
 
-
-
-
 /* include these first, according to the docs */
 #ifndef DMETAPHONE_MAIN
 
@@ -105,14 +102,19 @@ The remaining code is authored by Andrew Dunstan <amdunstan@ncshp.org> and
 
 /* turn off assertions for embedded function */
 #define NDEBUG
-#endif
 
+#else							/* DMETAPHONE_MAIN */
+
+/* we need these if we didn't get them from postgres.h */
 #include <stdio.h>
-#include <ctype.h>
 #include <stdlib.h>
 #include <string.h>
 #include <stdarg.h>
+
+#endif   /* DMETAPHONE_MAIN */
+
 #include <assert.h>
+#include <ctype.h>
 
 /* prototype for the main function we got from the perl module */
 static void DoubleMetaphone(char *, char **);