Fix inconsistencies in the code

This addresses a couple of issues in the code:
- Typos and inconsistencies in comments and function declarations.
- Removal of unreferenced function declarations.
- Removal of unnecessary compile flags.
- A cleanup error in regressplans.sh.

Author: Alexander Lakhin
Discussion: https://postgr.es/m/0c991fdf-2670-1997-c027-772a420c4604@gmail.com

src/interfaces/ecpg/ecpglib/ecpglib_extern.h

@@ -195,11 +195,8 @@ char	   *ecpg_strdup(const char *, int);
 const char *ecpg_type_name(enum ECPGttype);
 int			ecpg_dynamic_type(Oid);
 int			sqlda_dynamic_type(Oid, enum COMPAT_MODE);
-void		ecpg_free_auto_mem(void);
 void		ecpg_clear_auto_mem(void);
 
-struct descriptor *ecpggetdescp(int, char *);
-
 struct descriptor *ecpg_find_desc(int line, const char *name);
 
 struct prepared_statement *ecpg_find_prepared_statement(const char *,

src/interfaces/ecpg/ecpglib/execute.c

@@ -1899,7 +1899,7 @@ ecpg_process_output(struct statement *stmt, bool clear_result)
 
 			/*
 			 * execution should never reach this code because it is already
-			 * handled in ECPGcheck_PQresult()
+			 * handled in ecpg_check_PQresult()
 			 */
 			ecpg_log("ecpg_process_output on line %d: unknown execution status type\n",
 					 stmt->lineno);