clang doesn't have a problem with -Wnon-virtual-dtor

Even if some older version possibly does, I doubt anybody would
realistically use it.

solenv/gbuild/platform/unxgcc.mk

@@ -65,6 +65,7 @@ gb_CXXFLAGS := \
 	-Wsign-promo \
 	-Woverloaded-virtual \
 
+ifneq ($(COM_GCC_IS_CLANG),TRUE)
 # Only GCC 4.6 has a fix for <http://gcc.gnu.org/bugzilla/show_bug.cgi?id=7302>
 # "-Wnon-virtual-dtor should't complain of protected dtor" and supports #pragma
 # GCC diagnostic push/pop required e.g. in cppuhelper/propertysetmixin.hxx to
@@ -75,6 +76,9 @@ gb_CXXFLAGS += -Wno-non-virtual-dtor
 else
 gb_CXXFLAGS += -Wnon-virtual-dtor
 endif
+else
+gb_CXXFLAGS += -Wnon-virtual-dtor
+endif
 
 ifeq ($(HAVE_GCC_VISIBILITY_FEATURE),TRUE)
 gb_COMPILERDEFS += \

solenv/inc/unxgcc.mk

@@ -148,6 +148,7 @@ CFLAGSWALLCC=$(CFLAGSWARNCC)
 CFLAGSWALLCXX=$(CFLAGSWARNCXX)
 CFLAGSWERRCC=-Werror -DLIBO_WERROR
 
+.IF "$(COM_GCC_IS_CLANG)" != "TRUE"
 # Only GCC 4.6 has a fix for <http://gcc.gnu.org/bugzilla/show_bug.cgi?id=7302>
 # "-Wnon-virtual-dtor should't complain of protected dtor" and supports #pragma
 # GCC diagnostic push/pop required e.g. in cppuhelper/propertysetmixin.hxx to
@@ -158,6 +159,9 @@ CFLAGSWARNCXX += -Wno-non-virtual-dtor
 .ELSE
 CFLAGSWARNCXX += -Wnon-virtual-dtor
 .END
+.ELSE
+CFLAGSWARNCXX += -Wnon-virtual-dtor
+.END
 
 COMPILER_WARN_ERRORS=TRUE