runtime: jump instead of branch in netbsd/arm64 entry point

CL 706175 removed the NOFRAME directive from _rt0_arm64_netbsd but
did not change the BL instruction to a JMP instruction. This causes the
frame pointer to be stored on the stack, this making direct load from
RSP to be off by 8 bytes.

Cq-Include-Trybots: luci.golang.try:gotip-netbsd-arm64
Change-Id: I0c212fbaba74cfce508f961090dc6e66154c3054
Reviewed-on: https://go-review.googlesource.com/c/go/+/707675
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Michael Pratt <[email protected]>
Reviewed-by: Cherry Mui <[email protected]>

Author: qmuntal

src/runtime/rt0_netbsd_arm64.s

@@ -7,7 +7,7 @@
 TEXT _rt0_arm64_netbsd(SB),NOSPLIT,$0
 	MOVD	0(RSP), R0	// argc
 	ADD	$8, RSP, R1	// argv
-	BL	main(SB)
+	JMP	main(SB)
 
 // When building with -buildmode=c-shared, this symbol is called when the shared
 // library is loaded.