preproc: fix misparsing of << as right shift

Regression in commit 20e0d61.

Independently discovered and fixed by C. Masloch:
https://bugzilla.nasm.us/show_bug.cgi?id=3392747

Signed-off-by: Oleg Oshmyan <chortos@inbox.lv>

Author: astiob

asm/preproc.c

@@ -1613,7 +1613,7 @@ static Token *tokenize(const char *line)
 	    case '<':
 		if (*p == '<') {
 		    p++;
-                    type = TOKEN_SHR;
+                    type = TOKEN_SHL;
 		    if (*p == '<')
 			p++;
 		} else if (*p == '=') {