Using GCC compiler on the host breaks the build due to 'constexpr' being
a reserved keyword in C22.
Build expecting the sources to be in GNU17 standard fixes that.
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
The unifdef utility selectively processes conditional C preprocessor #if
and #ifdef directives. It is required to build WebKit ports.
Signed-off-by: Daniel Golle <daniel@makrotopia.org>