science/gnudatalanguage: unbreak with gcc6 on 10.*

src/CMakeFiles/gdl.dir/GDLInterpreter.cpp.o: In function `GDLInterpreter::l_decinc_dot_expr(ProgNode*, int)':
GDLInterpreter.cpp:(.text+0x4c24): undefined reference to `operator delete(void*, unsigned int)'
GDLInterpreter.cpp:(.text+0x4f51): undefined reference to `operator delete(void*, unsigned int)'
src/CMakeFiles/gdl.dir/GDLInterpreter.cpp.o: In function `GDLInterpreter::l_arrayexpr_mfcall_as_arrayexpr(ProgNode*, BaseGDL*)':
GDLInterpreter.cpp:(.text+0x51e9): undefined reference to `operator delete(void*, unsigned int)'
GDLInterpreter.cpp:(.text+0x5442): undefined reference to `operator delete(void*, unsigned int)'
src/CMakeFiles/gdl.dir/GDLInterpreter.cpp.o: In function `GDLInterpreter::l_arrayexpr_mfcall(ProgNode*, BaseGDL*)':
GDLInterpreter.cpp:(.text+0x5ab2): undefined reference to `operator delete(void*, unsigned int)'
src/CMakeFiles/gdl.dir/GDLInterpreter.cpp.o:GDLInterpreter.cpp:(.text._ZN5antlr15CharInputBufferD0Ev[_ZN5antlr15CharInputBufferD5Ev]+0x5d): more undefined references to `operator delete(void*, unsigned int)' follow
src/CMakeFiles/gdl.dir/basic_fun.cpp.o: In function `ForInfoListT<ForLoopInfoT, 32ull>::resize(unsigned long long)':
basic_fun.cpp:(.text._ZN12ForInfoListTI12ForLoopInfoTLy32EE6resizeEy[_ZN12ForInfoListTI12ForLoopInfoTLy32EE6resizeEy]+0x17e): undefined reference to `operator delete[](void*, unsigned int)'
src/CMakeFiles/gdl.dir/dcommon.cpp.o: In function `DCommon::~DCommon()':
dcommon.cpp:(.text+0xf5): undefined reference to `operator delete(void*, unsigned int)'
src/CMakeFiles/gdl.dir/dcommon.cpp.o: In function `DCommon::~DCommon()':
dcommon.cpp:(.text+0x154): undefined reference to `operator delete(void*, unsigned int)'
src/CMakeFiles/gdl.dir/dcommon.cpp.o: In function `DCommonRef::~DCommonRef()':
dcommon.cpp:(.text+0x3fd): undefined reference to `operator delete(void*, unsigned int)'
src/CMakeFiles/gdl.dir/dcommon.cpp.o: In function `DCommon::AddVar(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&)':
dcommon.cpp:(.text+0x482): undefined reference to `operator delete(void*, unsigned int)'
src/CMakeFiles/gdl.dir/dcompiler.cpp.o: In function `DCompiler::ForwardFunction(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&)':
dcompiler.cpp:(.text+0x226): undefined reference to `operator delete(void*, unsigned int)'
src/CMakeFiles/gdl.dir/dcompiler.cpp.o:dcompiler.cpp:(.text+0x314): more undefined references to `operator delete(void*, unsigned int)' follow
src/CMakeFiles/gdl.dir/envt.cpp.o: In function `ForInfoListT<ForLoopInfoT, 32ull>::~ForInfoListT()':
envt.cpp:(.text._ZN12ForInfoListTI12ForLoopInfoTLy32EED2Ev[_ZN12ForInfoListTI12ForLoopInfoTLy32EED5Ev]+0x76): undefined reference to `operator delete[](void*, unsigned int)'
src/CMakeFiles/gdl.dir/envt.cpp.o: In function `EnvUDT::~EnvUDT()':
envt.cpp:(.text._ZN6EnvUDTD2Ev[_ZN6EnvUDTD5Ev]+0xca): undefined reference to `operator delete(void*, unsigned int)'
src/CMakeFiles/gdl.dir/extrat.cpp.o: In function `ExtraT::ResolveExtra(EnvBaseT*)':
extrat.cpp:(.text+0x1aaa): undefined reference to `operator delete(void*, unsigned int)'
src/CMakeFiles/gdl.dir/fmtnode.cpp.o: In function `FMTNode::~FMTNode()':
fmtnode.cpp:(.text+0x44): undefined reference to `operator delete(void*, unsigned int)'
src/CMakeFiles/gdl.dir/gdlexception.cpp.o: In function `WarnAboutObsoleteRoutine(antlr::ASTRefCount<DNode>, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&)':
gdlexception.cpp:(.text+0x1c6f): undefined reference to `operator delete(void*, unsigned int)'
gdlexception.cpp:(.text+0x1eab): undefined reference to `operator delete(void*, unsigned int)'
src/CMakeFiles/gdl.dir/gdlxstream.cpp.o:gdlxstream.cpp:(.text._ZN10GDLXStreamD0Ev[_ZN10GDLXStreamD5Ev]+0x1d): more undefined references to `operator delete(void*, unsigned int)' follow

PR:		219300
Reported by:	pkg-fallout
Submitted by:	rakuco

science/gnudatalanguage/Makefile

@@ -26,6 +26,13 @@ USE_WX=		3.0+
 USE_XORG=	x11 sm ice xext
 USES=		cmake:outsource compiler:gcc-c++11-lib dos2unix ncurses pkgconfig readline tar:tgz
 
+# On FreeBSD < 11 libc++ lacks support for sized delete operators.
+# GCC dropped the builtin version of these operators in 6+ by
+# defaulting to gnu++14. Force c++11 instead.
+# For a more detailed discussion see:
+# https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=219484
+USE_CXXSTD=	gnu++11
+
 # Disable ncurses and readline from ports
 # Disable ImageMagick (does'nt work with plplot because dynamic drivers
 #	are enabled by default)