Add build option to force building without external libudfread

configure.ac

@@ -132,6 +132,12 @@ AC_ARG_WITH([bdj-bootclasspath],
 AC_ARG_WITH([java9],
   [AS_HELP_STRING([--with-java9], [build with Java 9+ (drop support for Java <1.6) @<:@default=without@:>@])])
 
+AC_ARG_WITH([external-libudfread],
+  [AS_HELP_STRING([--without-external-libudfread],
+  [build without external libudfread @<:@default=with@:>@])],
+  [with_external_libudfread=$withwal],
+  [with_external_libudfread=yes])
+
 dnl required programs
 AC_PROG_CC
 AM_PROG_CC_C_O
@@ -310,11 +316,14 @@ AM_CONDITIONAL([BDJ_J2SE], [ test x"$BDJ_TYPE" != x"j2me" ])
 dnl bootclasspath
 AC_SUBST(BDJ_BOOTCLASSPATH)
 
-PKG_CHECK_MODULES([LIBUDFREAD], [libudfread >= 1.1.0],
-    [with_libudfread=yes
-     AC_DEFINE([HAVE_LIBUDFREAD], [1], [Define to 1 if external libudfread is to be used])
-     PACKAGES="$PACKAGES libudfread >= 1.1.0"
-    ],[
+AS_IF([test "x$with_external_libudfread" = "xyes"], [
+    PKG_CHECK_MODULES([LIBUDFREAD], [libudfread >= 1.1.0],
+        [with_libudfread=yes
+         AC_DEFINE([HAVE_LIBUDFREAD], [1], [Define to 1 if external libudfread is to be used])
+         PACKAGES="$PACKAGES libudfread >= 1.1.0"
+        ],[break;])
+])
+AS_IF([test "x$with_libudfread" != "xyes"], [
      dnl udf support (using git submodule)
      with_libudfread=no
      AS_IF([test ! -f "${srcdir}/contrib/libudfread/src/udfread.h"], [AC_MSG_ERROR("libudfread source tree not found")])