ibrcommon: fix dependencies of comment in Config.in

We want the comment to be displayed either if C++ is not supported
*or* if threads is not supported.

Also, fix the indentation to use a tab.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/ibrcommon/Config.in

@@ -10,5 +10,4 @@ config BR2_PACKAGE_IBRCOMMON
 	  http://trac.ibr.cs.tu-bs.de/project-cm-2012-ibrdtn
 
 comment "ibrcommon needs a toolchain w/ C++, threads"
-        depends on !BR2_INSTALL_LIBSTDCPP
-	depends on !BR2_TOOLCHAIN_HAS_THREADS
+	depends on !BR2_INSTALL_LIBSTDCPP || !BR2_TOOLCHAIN_HAS_THREADS