Update buildroot v2020.02.4 (#811)

* Update buildroot to 2020.02.4

Signed-off-by: Pascal Vizeli <pvizeli@syshack.ch>

* fix patches

Signed-off-by: Pascal Vizeli <pvizeli@syshack.ch>

buildroot/toolchain/toolchain-wrapper.c

@@ -177,6 +177,7 @@ static void check_unsafe_path(const char *arg,
 	}
 }
 
+#ifdef BR_NEED_SOURCE_DATE_EPOCH
 /* Returns false if SOURCE_DATE_EPOCH was not defined in the environment.
  *
  * Returns true if SOURCE_DATE_EPOCH is in the environment and represent
@@ -230,6 +231,15 @@ bool parse_source_date_epoch_from_env(void)
 	}
 	return true;
 }
+#else
+bool parse_source_date_epoch_from_env(void)
+{
+	/* The compiler is recent enough to handle SOURCE_DATE_EPOCH itself
+	 * so we do not need to do anything here.
+	 */
+	return false;
+}
+#endif
 
 int main(int argc, char **argv)
 {