feat(asm): symbol-valued DATA, division slash in symbols and plain semicolons

Assisted-by: GLM 5.3 Flash

testdata/verify/datarel_arm64.s

@@ -0,0 +1,25 @@
+#include "textflag.h"
+
+// The kernel exercises the symbol-valued DATA spelling the runtime's rt0
+// files use: a data word holding the address of a symbol, resolved by the
+// linker through a relocation at the field.
+
+// func lookup() ptr
+TEXT ·lookup(SB), NOSPLIT, $0-8
+	MOVD handlers+8(SB), R4
+	MOVD R4, ret+0(FP)
+	RET
+
+// func handler() int64
+TEXT ·handler(SB), NOSPLIT, $0-8
+	MOVZ $42, R4
+	MOVD R4, ret+0(FP)
+	RET
+
+GLOBL handlers(SB), NOPTR, $24
+DATA handlers+0(SB)/8, $·handler(SB)
+DATA handlers+8(SB)/8, $table(SB)
+DATA handlers+16(SB)/8, $extentry(SB)
+
+GLOBL table(SB), RODATA, $8
+DATA table+0(SB)/8, $0x123456789abcdef0