shells/nushell: fix build on armv7

 - mark as LTO_UNSAFE on armv6/armv7 to avoid address space
   exhaustion
 - remove custom do-test target to avoid a conflict with cargo.mk's
   do-test; cargo.mk's default do-test does the job well enough

Approved by:	portmgr (build fix blanket)
MFH:		2023Q4

shells/nushell/Makefile

@@ -607,10 +607,14 @@ DATAFRAME_DESC=		Include the dataframe feature
 DATAFRAME_VARS=		CARGO_BUILD_ARGS+=--features=dataframe
 DATAFRAME_BROKEN=	see https://github.com/nushell/nushell/issues/7665
 
+.include <bsd.port.pre.mk>
+
+# avoid address space exhaustion in compiler
+.if ${ARCH:Marmv?}
+LTO_UNSAFE=	yes
+.endif
+
 post-install:
 	@${STRIP_CMD} ${STAGEDIR}${PREFIX}/bin/nu
 
-do-test:
-	@${CARGO_CARGO_RUN} test --workspace
-
-.include <bsd.port.mk>
+.include <bsd.port.post.mk>