package/sdbus-cpp: remove redundant SDBUS_CPP_SOURCE variable

There is no need to define SDBUS_CPP_SOURCE explicitly because the
github helper works perfectly well with the default _SOURCE value.

Signed-off-by: Sergey Bobrenok <bobrofon@gmail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

package/sdbus-cpp/sdbus-cpp.hash

@@ -1,4 +1,4 @@
 # Locally computed:
-sha256  ca7405c7f0f9ae3023dcfa37bc68974c4b8a1c9ea2909b970e0aedc3e8657ee6  v1.4.0.tar.gz
+sha256  ca7405c7f0f9ae3023dcfa37bc68974c4b8a1c9ea2909b970e0aedc3e8657ee6  sdbus-cpp-1.4.0.tar.gz
 sha256  20c17d8b8c48a600800dfd14f95d5cb9ff47066a9641ddeab48dc54aec96e331  COPYING
 sha256  a1c9e75e25d8f2ce18017c88978edab2f0dbc7814ad0697d4ff2e5e59959f657  COPYING-LGPL-Exception

package/sdbus-cpp/sdbus-cpp.mk

@@ -5,7 +5,6 @@
 ################################################################################
 
 SDBUS_CPP_VERSION = 1.4.0
-SDBUS_CPP_SOURCE = v$(SDBUS_CPP_VERSION).tar.gz
 SDBUS_CPP_SITE = $(call github,Kistler-Group,sdbus-cpp,v$(SDBUS_CPP_VERSION))
 SDBUS_CPP_INSTALL_STAGING = YES
 SDBUS_CPP_DEPENDENCIES = host-pkgconf systemd