Bug 574874 - Disable full gdb console support if running CDT in flatpak

- add check for flatpak environment variable in
  GDBBackend_7_12.isFullGdbConsoleSupported() method
  and return false if variable is set

Change-Id: I667a63395592e2671ab3bf6f255e7428371086b3
diff --git a/dsf-gdb/org.eclipse.cdt.dsf.gdb/src/org/eclipse/cdt/dsf/gdb/service/GDBBackend_7_12.java b/dsf-gdb/org.eclipse.cdt.dsf.gdb/src/org/eclipse/cdt/dsf/gdb/service/GDBBackend_7_12.java
index 2c2b128..d5652d1 100644
--- a/dsf-gdb/org.eclipse.cdt.dsf.gdb/src/org/eclipse/cdt/dsf/gdb/service/GDBBackend_7_12.java
+++ b/dsf-gdb/org.eclipse.cdt.dsf.gdb/src/org/eclipse/cdt/dsf/gdb/service/GDBBackend_7_12.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2016 Ericsson and others.
+ * Copyright (c) 2016, 2021 Ericsson and others.
  *
  * This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License 2.0
@@ -59,7 +59,8 @@
 
 	@Override
 	public boolean isFullGdbConsoleSupported() {
-		return !Platform.getOS().equals(Platform.OS_WIN32) && !Platform.getOS().equals(Platform.OS_MACOSX)
+		return System.getenv("FLATPAK_SANDBOX_DIR") == null //$NON-NLS-1$
+				&& !Platform.getOS().equals(Platform.OS_WIN32) && !Platform.getOS().equals(Platform.OS_MACOSX)
 				&& !fPtyFailure;
 	}