"make example" builds example.c if libgcrypt present

using AM_PATH_LIBGCRYPT to check for libgcrypt

removed AC_MSG_RESULT in configure.ac; added phony "example" target in Makefile.am if libcrypt not found

configure.ac

@@ -51,4 +51,18 @@ PKG_CHECK_MODULES([libbase58],[libbase58])
 
 AC_CHECK_LIB([ws2_32], [strchr])
 
+#libgcrypt necessary to build example.c with "make example"
+#check for libgcrypt:
+m4_ifdef([AM_PATH_LIBGCRYPT], [
+	AM_PATH_LIBGCRYPT([],
+		[
+			[can_compile_example=yes]
+		],[
+			[compile_example=no]
+		])
+],[
+        m4_warn([syntax], [AM_PATH_LIBGCRYPT missing; CLI tool will not be available])
+])
+AM_CONDITIONAL([CAN_COMPILE_EXAMPLE], [test x$can_compile_example = xyes])
+
 AC_OUTPUT