ob-core: Speed improvement

* lisp/ob-core.el (org-babel-get-inline-src-block-matches): Do not
  compute line number if all is needed is to know if we're on the
  first one.

lisp/ob-core.el

@@ -217,7 +217,7 @@ Returns non-nil if match-data set"
   (let ((src-at-0-p (save-excursion
 		      (beginning-of-line 1)
 		      (string= "src" (thing-at-point 'word))))
-	(first-line-p (= 1 (line-number-at-pos)))
+	(first-line-p (= (line-beginning-position) (point-min)))
 	(orig (point)))
     (let ((search-for (cond ((and src-at-0-p first-line-p  "src_"))
 			    (first-line-p "[[:punct:] \t]src_")