Build failure triggers on CXXFLAGS=-Werror=terminate

  cmdline.cpp: In destructor ‘virtual XxCmdline::~XxCmdline()’:
  ./defs.h:121:43: error: throw will always call terminate() [-Werror=terminate]
      { throw XxInternalError( XX_EXC_PARAMS ); }                                           ^
  cmdline.cpp:369:7: note: in expansion of macro ‘XX_ASSERT’

https://bugs.gentoo.org/601018
diff --git a/src/cmdline.cpp b/src/cmdline.cpp
index 8cb0ac9..174b9a4 100644
--- a/src/cmdline.cpp
+++ b/src/cmdline.cpp
@@ -368,3 +368,2 @@ XxCmdline::~XxCmdline()
    for ( int ii = 0; ii < _nbQtOptions; ++ii ) {
-      XX_ASSERT( _qtOptions[ii] != 0 );
 #ifndef WINDOWS