insns.dat: reinstate TEST reg,mem alias

Officially the syntax for TEST is "rm,reg"; however TEST is
commutative in every aspect, and as such "reg,mem" is an equivalent
form that NASM has also supported in the past.

Reinstate it properly.

Fixes: https://bugzilla.nasm.us/show_bug.cgi?id=3392962
Reported-by: E. C. Masloch <pushbx@ulukai.org>
Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>

Author: H. Peter Anvin

travis/test/testmem.asm

@@ -0,0 +1,11 @@
+	bits 64
+
+	test al,[rbx]
+	test ax,[rbx]
+	test eax,[rbx]
+	test rax,[rbx]
+
+	test cl,[rbx]
+	test cx,[rbx]
+	test ecx,[rbx]
+	test rcx,[rbx]

travis/test/testmem.bin.t

@@ -0,0 +1 @@
+�f��H��f��H�

travis/test/testmem.json

@@ -0,0 +1,11 @@
+[
+    {
+	"description": "Test TEST reg,mem instruction alias",
+	"id": "testmem",
+	"format": "bin",
+	"source": "testmem.asm",
+	"target": [
+	    { "output": "testmem.bin" }
+	]
+    }
+]

x86/insns.dat

@@ -73,6 +73,7 @@ $arith		nf=nf ADD OR nf=,ADC nf=,SBB AND SUB XOR nf=,!evex,CMP
 
 ;# Bitwise testing
 $bwdq TEST	rm#,reg#			[mr:	o# 84# /r		]		8086,SM
+$bwdq TEST	reg#,mem#			[rm:	o# 84# /r		]		8086,SM,ND
 $bwdq TEST	ax#,imm#			[-i:	o# a8# i#		]		8086,SM,NOAPX
 $bwdq TEST	rm#,imm#			[mi:	o# f6# /0 i#		]		8086,SM