pcre2test: use the right header for libedit in FreeBSD with autoconf

When `./configure --enable-pcre2test-libedit` is used in FreeBSD,
the resulting test will succeed but won't set the necessary flag
to distinguish between libedit and readline header files, therefore
using readline's at built time (if installed)

Consolidate all header tests into one and use instead the corresponding
autogenerated defines to check for each possibility.

configure.ac

@@ -597,14 +597,14 @@ if test "$enable_pcre2test_libreadline" = "yes"; then
  fi
 fi
 
-
 # Check for the availability of libedit. Different distributions put its
 # headers in different places. Try to cover the most common ones.
 
 if test "$enable_pcre2test_libedit" = "yes"; then
-  AC_CHECK_HEADERS([editline/readline.h], [HAVE_EDITLINE_READLINE_H=1],
-    [AC_CHECK_HEADERS([edit/readline/readline.h], [HAVE_READLINE_READLINE_H=1],
-      [AC_CHECK_HEADERS([readline/readline.h], [HAVE_READLINE_READLINE_H=1])])])
+  AC_CHECK_HEADERS([editline/readline.h edit/readline/readline.h readline/readline.h], [
+    HAVE_LIBEDIT_HEADER=1
+    break
+  ])
   AC_CHECK_LIB([edit], [readline], [LIBEDIT="-ledit"])
 fi
 
@@ -940,8 +940,7 @@ if test "$enable_pcre2test_libedit" = "yes"; then
     echo "** Cannot use both --enable-pcre2test-libedit and --enable-pcre2test-readline"
     exit 1
   fi
-  if test "$HAVE_EDITLINE_READLINE_H" != "1" -a \
-          "$HAVE_READLINE_READLINE_H" != "1"; then
+  if test -z "$HAVE_LIBEDIT_HEADER"; then
     echo "** Cannot --enable-pcre2test-libedit because neither editline/readline.h"
     echo "** nor readline/readline.h was found."
     exit 1

src/pcre2test.c

@@ -94,6 +94,8 @@ that first, falling back to readline/readline.h. */
 #else
 #if defined(HAVE_EDITLINE_READLINE_H)
 #include <editline/readline.h>
+#elif defined(HAVE_EDIT_READLINE_READLINE_H)
+#include <edit/readline/readline.h>
 #else
 #include <readline/readline.h>
 #endif