graphics/libglvnd: disable TLS on powerpc

libGLdispatch.so.0`___lldb_unnamed_symbol96:
->  0x51346dac <+4>:  .long  0x0005e290                ; unknown opcode

graphics/libglvnd/Makefile

@@ -1,6 +1,6 @@
 PORTNAME=	libglvnd
 DISTVERSION=	1.6.0
-PORTREVISION=	1
+PORTREVISION=	2
 CATEGORIES=	graphics
 
 MAINTAINER=	x11@FreeBSD.org
@@ -32,6 +32,10 @@ X11_MESON_ENABLED=	x11 glx
 MESON_ARGS+=	-Dasm=disabled
 .endif
 
+.if ${ARCH} == powerpc
+MESON_ARGS+=	-Dtls=false
+.endif
+
 # Lots of software expects gl.pc even when it can build with EGL only
 post-install-X11-off:
 	${LN} -s opengl.pc ${STAGEDIR}${PREFIX}/libdata/pkgconfig/gl.pc