Allow building dblib with machine-dependent libdir

Use the same approach as for GMP: If no explicit directory is
given, assume it must be on the default include path and libdir.
Otherwise use the provided path. It does not look like libsybdb
has support for pkg-config.

Author: nikic

ext/pdo_dblib/config.m4

@@ -10,23 +10,13 @@ if test "$PHP_PDO_DBLIB" != "no"; then
   fi
 
   if test "$PHP_PDO_DBLIB" = "yes"; then
-
-    for i in /usr/local /usr; do
-      if test -f $i/include/sybdb.h; then
-        PDO_FREETDS_INSTALLATION_DIR=$i
-        PDO_FREETDS_INCLUDE_DIR=$i/include
-        break
-      elif test -f $i/include/freetds/sybdb.h; then
-        PDO_FREETDS_INSTALLATION_DIR=$i
-        PDO_FREETDS_INCLUDE_DIR=$i/include/freetds
-        break;
-      fi
-    done
-
-    if test -z "$PDO_FREETDS_INSTALLATION_DIR"; then
-      AC_MSG_ERROR(Cannot find FreeTDS in known installation directories)
-    fi
-
+    dnl FreeTDS must be on the default system include/library path.
+    dnl Only perform a sanity check that this is really the case.
+    PHP_CHECK_LIBRARY(sybdb, dbsqlexec,
+    [],[
+      AC_MSG_ERROR([Cannot find FreeTDS in known installation directories])
+    ])
+    PHP_ADD_LIBRARY(sybdb,,GMP_SHARED_LIBADD)
   elif test "$PHP_PDO_DBLIB" != "no"; then
 
     if test -f $PHP_PDO_DBLIB/include/sybdb.h; then
@@ -38,18 +28,18 @@ if test "$PHP_PDO_DBLIB" != "no"; then
     else
       AC_MSG_ERROR(Directory $PHP_PDO_DBLIB is not a FreeTDS installation directory)
     fi
-  fi
 
-  if test "x$PHP_LIBDIR" = "x" ; then
-    PHP_LIBDIR=lib
-  fi
+    if test "x$PHP_LIBDIR" = "x" ; then
+      PHP_LIBDIR=lib
+    fi
 
-  if test ! -r "$PDO_FREETDS_INSTALLATION_DIR/$PHP_LIBDIR/libsybdb.a" && test ! -r "$PDO_FREETDS_INSTALLATION_DIR/$PHP_LIBDIR/libsybdb.so"; then
-     AC_MSG_ERROR(Could not find $PDO_FREETDS_INSTALLATION_DIR/$PHP_LIBDIR/libsybdb.[a|so])
-  fi
+    if test ! -r "$PDO_FREETDS_INSTALLATION_DIR/$PHP_LIBDIR/libsybdb.a" && test ! -r "$PDO_FREETDS_INSTALLATION_DIR/$PHP_LIBDIR/libsybdb.so"; then
+       AC_MSG_ERROR(Could not find $PDO_FREETDS_INSTALLATION_DIR/$PHP_LIBDIR/libsybdb.[a|so])
+    fi
 
-  PHP_ADD_INCLUDE($PDO_FREETDS_INCLUDE_DIR)
-  PHP_ADD_LIBRARY_WITH_PATH(sybdb, $PDO_FREETDS_INSTALLATION_DIR/$PHP_LIBDIR, PDO_DBLIB_SHARED_LIBADD)
+    PHP_ADD_INCLUDE($PDO_FREETDS_INCLUDE_DIR)
+    PHP_ADD_LIBRARY_WITH_PATH(sybdb, $PDO_FREETDS_INSTALLATION_DIR/$PHP_LIBDIR, PDO_DBLIB_SHARED_LIBADD)
+  fi
 
   PHP_CHECK_PDO_INCLUDES