More regexp corrections and tweaks

Problems reported by Mattias Engdegård in:
https://lists.gnu.org/r/emacs-devel/2019-03/msg00247.html
* lisp/align.el (align-rules-list):
* lisp/comint.el (comint-output-filter):
* lisp/language/china-util.el (encode-hz-region):
* lisp/progmodes/cperl-mode.el (cperl-indent-exp):
* lisp/progmodes/idlwave.el (idlwave-is-pointer-dereference):
* lisp/progmodes/scheme.el (dsssl-font-lock-keywords):
* lisp/textmodes/texinfmt.el (texinfo-accent-commands):
* test/src/regex-emacs-tests.el (regex-tests-re-even-escapes):
Fix some regular-expression typos.

lisp/align.el

@@ -399,7 +399,7 @@ The possible settings for `align-region-separate' are:
 		   (lambda (end reverse)
 		     (funcall (if reverse 're-search-backward
 				're-search-forward)
-			      (concat "[^ \t\n\\\\]"
+			      (concat "[^ \t\n\\]"
 				      (regexp-quote comment-start)
 				      "\\(.+\\)$") end t))))
      (modes    . align-open-comment-modes))

lisp/comint.el

@@ -2081,7 +2081,7 @@ Make backspaces delete the previous character."
                        (prompt-re (concat "\\`" (regexp-quote prompt))))
                   (while (string-match prompt-re string)
                     (setq string (substring string (match-end 0)))))))
-            (while (string-match (concat "\\(^" comint-prompt-regexp
+            (while (string-match (concat "\\(" comint-prompt-regexp
                                          "\\)\\1+")
                                  string)
               (setq string (replace-match "\\1" nil nil string)))

lisp/language/china-util.el

@@ -168,7 +168,7 @@ Return the length of resulting text."
 	      ;; ESC ESC -> ESC
 	      (delete-char 1)
 	    (forward-char -1)
-	    (if (looking-at iso2022-gb-designation)
+	    (if (looking-at "\e\\$A")
 		(progn
 		  (delete-region (match-beginning 0) (match-end 0))
 		  (insert hz-gb-designation)

lisp/progmodes/cperl-mode.el

@@ -4924,7 +4924,7 @@ conditional/loop constructs."
 			      (if (looking-at "\\(state\\|my\\|local\\|our\\)\\>")
 				  (forward-sexp -1))))
 			(if (looking-at
-			     (concat "\\(\\elsif\\|if\\|unless\\|while\\|until"
+			     (concat "\\(elsif\\|if\\|unless\\|while\\|until"
 				     "\\|for\\(each\\)?\\>\\(\\("
 				     cperl-maybe-white-and-comment-rex
 				     "\\(state\\|my\\|local\\|our\\)\\)?"

lisp/progmodes/idlwave.el

@@ -3690,7 +3690,7 @@ constants - a double quote followed by an octal digit."
    (save-excursion
      (forward-char)
      (re-search-backward (concat "\\(" idlwave-idl-keywords
-                                 "\\|[[(*+-/=,^><]\\)\\s-*\\*") limit t))))
+                                 "\\|[-[(*+/=,^><]\\)\\s-*\\*") limit t))))
 
 
 ;; Statement templates

lisp/progmodes/scheme.el

@@ -433,7 +433,7 @@ that variable's value is a string."
               ;; (make-regexp '("case" "cond" "else" "if" "lambda"
               ;; "let" "let*" "letrec" "and" "or" "map" "with-mode"))
               "and\\|c\\(ase\\|ond\\)\\|else\\|if\\|"
-              "l\\(ambda\\|et\\(\\|*\\|rec\\)\\)\\|map\\|or\\|with-mode"
+              "l\\(ambda\\|et\\(\\|\\*\\|rec\\)\\)\\|map\\|or\\|with-mode"
               "\\)\\>")
       1)
      ;; DSSSL syntax

lisp/textmodes/texinfmt.el

@@ -552,13 +552,7 @@ if large.  You can use `Info-split' to do this manually."
 
 (defvar texinfo-accent-commands
   (concat
-   "@^\\|"
-   "@`\\|"
-   "@'\\|"
-   "@\"\\|"
-   "@,\\|"
-   "@=\\|"
-   "@~\\|"
+   "@[\"',=^`~]\\|"
    "@OE{\\|"
    "@oe{\\|"
    "@AA{\\|"

test/src/regex-emacs-tests.el

@@ -278,7 +278,7 @@ on success"
 
 
 (defconst regex-tests-re-even-escapes
-  "\\(?:^\\|[^\\\\]\\)\\(?:\\\\\\\\\\)*"
+  "\\(?:^\\|[^\\]\\)\\(?:\\\\\\\\\\)*"
   "Regex that matches an even number of \\ characters")
 
 (defconst regex-tests-re-odd-escapes