Move gramparse.h to src/backend/parser

This header is semi-private, being used only in files related to
raw parsing, so move to the backend directory where those files
live. This allows removal of Makefile rules that symlink gram.h to
src/include/parser, since gramparse.h can now include gram.h from
within the same directory. This has the side-effect of no longer
installing gram.h and gramparse.h, but there doesn't seem to be a
good reason to continue doing so.

Per suggestion from Andres Freund and Peter Eisentraut
Discussion: https://www.postgresql.org/message-id/20220904181759.px6uosll6zbxcum5%40awork3.anarazel.de

src/backend/parser/gram.y

@@ -55,9 +55,9 @@
 #include "catalog/pg_trigger.h"
 #include "commands/defrem.h"
 #include "commands/trigger.h"
+#include "gramparse.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
-#include "parser/gramparse.h"
 #include "parser/parser.h"
 #include "storage/lmgr.h"
 #include "utils/date.h"

src/backend/parser/gramparse.h

@@ -0,0 +1,75 @@
+/*-------------------------------------------------------------------------
+ *
+ * gramparse.h
+ *		Shared definitions for the "raw" parser (flex and bison phases only)
+ *
+ * NOTE: this file is only meant to be included in the core parsing files,
+ * i.e., parser.c, gram.y, and scan.l.
+ * Definitions that are needed outside the core parser should be in parser.h.
+ *
+ *
+ * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/backend/parser/gramparse.h
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#ifndef GRAMPARSE_H
+#define GRAMPARSE_H
+
+#include "nodes/parsenodes.h"
+#include "parser/scanner.h"
+
+/*
+ * NB: include gram.h only AFTER including scanner.h, because scanner.h
+ * is what #defines YYLTYPE.
+ */
+#include "gram.h"
+
+/*
+ * The YY_EXTRA data that a flex scanner allows us to pass around.  Private
+ * state needed for raw parsing/lexing goes here.
+ */
+typedef struct base_yy_extra_type
+{
+	/*
+	 * Fields used by the core scanner.
+	 */
+	core_yy_extra_type core_yy_extra;
+
+	/*
+	 * State variables for base_yylex().
+	 */
+	bool		have_lookahead; /* is lookahead info valid? */
+	int			lookahead_token;	/* one-token lookahead */
+	core_YYSTYPE lookahead_yylval;	/* yylval for lookahead token */
+	YYLTYPE		lookahead_yylloc;	/* yylloc for lookahead token */
+	char	   *lookahead_end;	/* end of current token */
+	char		lookahead_hold_char;	/* to be put back at *lookahead_end */
+
+	/*
+	 * State variables that belong to the grammar.
+	 */
+	List	   *parsetree;		/* final parse result is delivered here */
+} base_yy_extra_type;
+
+/*
+ * In principle we should use yyget_extra() to fetch the yyextra field
+ * from a yyscanner struct.  However, flex always puts that field first,
+ * and this is sufficiently performance-critical to make it seem worth
+ * cheating a bit to use an inline macro.
+ */
+#define pg_yyget_extra(yyscanner) (*((base_yy_extra_type **) (yyscanner)))
+
+
+/* from parser.c */
+extern int	base_yylex(YYSTYPE *lvalp, YYLTYPE *llocp,
+					   core_yyscan_t yyscanner);
+
+/* from gram.y */
+extern void parser_init(base_yy_extra_type *yyext);
+extern int	base_yyparse(core_yyscan_t yyscanner);
+
+#endif							/* GRAMPARSE_H */

src/backend/parser/parser.c

@@ -22,7 +22,7 @@
 #include "postgres.h"
 
 #include "mb/pg_wchar.h"
-#include "parser/gramparse.h"
+#include "gramparse.h"
 #include "parser/parser.h"
 #include "parser/scansup.h"
 

src/backend/parser/scan.l

@@ -36,7 +36,7 @@
 #include <unistd.h>
 
 #include "common/string.h"
-#include "parser/gramparse.h"
+#include "gramparse.h"
 #include "parser/parser.h"		/* only needed for GUC variables */
 #include "parser/scansup.h"
 #include "port/pg_bitutils.h"