Add "%option warn" to all flex input files that lacked it.

This is recommended in the flex manual, and there seems no good reason
not to use it everywhere.

Author: tglsfdc

contrib/cube/cubescan.l

@@ -32,6 +32,7 @@ void cube_scanner_finish(void);
 %option noinput
 %option nounput
 %option noyywrap
+%option warn
 %option prefix="cube_yy"
 
 

contrib/seg/segscan.l

@@ -30,6 +30,7 @@ void seg_scanner_finish(void);
 %option noinput
 %option nounput
 %option noyywrap
+%option warn
 %option prefix="seg_yy"
 
 

src/backend/bootstrap/bootscanner.l

@@ -55,6 +55,7 @@ static int	yyline = 1;			/* line number for error reporting */
 %option noinput
 %option nounput
 %option noyywrap
+%option warn
 %option prefix="boot_yy"
 
 

src/backend/utils/misc/guc-file.l

@@ -51,6 +51,7 @@ static char *GUC_scanstr(const char *s);
 %option noinput
 %option nounput
 %option noyywrap
+%option warn
 %option prefix="GUC_yy"
 
 

src/bin/psql/psqlscan.l

@@ -132,6 +132,7 @@ static void escape_variable(bool as_ident);
 %option noinput
 %option nounput
 %option noyywrap
+%option warn
 
 /*
  * All of the following definitions and rules should exactly match

src/interfaces/ecpg/preproc/pgc.l

@@ -84,6 +84,7 @@ static struct _if_value
 %option nodefault
 %option noinput
 %option noyywrap
+%option warn
 
 %option yylineno
 

src/test/isolation/specscanner.l

@@ -15,7 +15,7 @@ static int	yyline = 1;			/* line number for error reporting */
 static char litbuf[1024];
 static int litbufpos = 0;
 
-static void addlitchar(const char c);
+static void addlitchar(char c);
 
 %}
 
@@ -25,6 +25,7 @@ static void addlitchar(const char c);
 %option noinput
 %option nounput
 %option noyywrap
+%option warn
 %option prefix="spec_yy"
 
 
@@ -93,7 +94,7 @@ teardown		{ return(TEARDOWN); }
 %%
 
 static void
-addlitchar(const char c)
+addlitchar(char c)
 {
   if (litbufpos >= sizeof(litbuf) - 1)
   {