test/codegen: simplify asmcheck pattern matching

Separate patterns in asmcheck by spaces instead of commas.
Many patterns end in comma (like "MOV [$]123,") so separating
patterns by comma is not great; they're already quoted, so spaces are fine.

Also replace all tabs in the assembly lines with spaces before matching.
Finally, replace \$ or \\$ with [$] as the matching idiom.
The effect of all these is to make the patterns look like:

  	   // amd64:"BSFQ" "ORQ [$]256"

instead of the old:

  	   // amd64:"BSFQ","ORQ\t\\$256"

Update all tests as well.

Change-Id: Ia39febe5d7f67ba115846422789e11b185d5c807
Reviewed-on: https://go-review.googlesource.com/c/go/+/716060
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Alan Donovan <adonovan@google.com>
Reviewed-by: Jorropo <jorropo.pgm@gmail.com>

test/codegen/logic.go

@@ -28,14 +28,14 @@ func ornot(x, y int) int {
 
 // Verify that (OR (NOT x) (NOT y)) rewrites to (NOT (AND x y))
 func orDemorgans(x, y int) int {
-	// amd64:"AND",-"OR"
+	// amd64:"AND" -"OR"
 	z := ^x | ^y
 	return z
 }
 
 // Verify that (AND (NOT x) (NOT y)) rewrites to (NOT (OR x y))
 func andDemorgans(x, y int) int {
-	// amd64:"OR",-"AND"
+	// amd64:"OR" -"AND"
 	z := ^x & ^y
 	return z
 }