hush: fix handling of \" in quoted/unquoted `cmd`

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
diff --git a/shell/hush_test/hush-misc/heredoc_backslash1.tests b/shell/hush_test/hush-misc/heredoc_backslash1.tests
index 22045d4..501af54 100755
--- a/shell/hush_test/hush-misc/heredoc_backslash1.tests
+++ b/shell/hush_test/hush-misc/heredoc_backslash1.tests
@@ -11,6 +11,8 @@
 	b
  123456 -$a-\t-\\-\"-\'-\`-\--\z-\*-\?-
 	-$a-\t-\\-\"-\'-\`-\--\z-\*-\?-
+ 123456 `echo  v'-$a-\t-\\-\"-\'-\`-\--\z-\*-\?-'`
+ 123456 $(echo v'-$a-\t-\\-\"-\'-\`-\--\z-\*-\?-')
 c\
 EOF1
 echo
@@ -23,6 +25,8 @@
 	b
  123456 -$a-\t-\\-\"-\'-\`-\--\z-\*-\?-
 	-$a-\t-\\-\"-\'-\`-\--\z-\*-\?-
+ 123456 `echo  v'-$a-\t-\\-\"-\x-\`-\--\z-\*-\?-'`
+ 123456 $(echo v'-$a-\t-\\-\"-\x-\`-\--\z-\*-\?-')
 c\
 EOF2
 EOF2
@@ -36,6 +40,8 @@
 	b
  123456 -$a-\t-\\-\"-\'-\`-\--\z-\*-\?-
 	-$a-\t-\\-\"-\'-\`-\--\z-\*-\?-
+ 123456 `echo  v'-$a-\t-\\-\"-\'-\`-\--\z-\*-\?-'`
+ 123456 $(echo v'-$a-\t-\\-\"-\'-\`-\--\z-\*-\?-')
 c\
 	EOF3
 # In -heredoc case the marker is detected even if it is indented.
@@ -49,6 +55,8 @@
 	b
  123456 -$a-\t-\\-\"-\'-\`-\--\z-\*-\?-
 	-$a-\t-\\-\"-\'-\`-\--\z-\*-\?-
+ 123456 `echo  v'-$a-\t-\\-\"-\x-\`-\--\z-\*-\?-'`
+ 123456 $(echo v'-$a-\t-\\-\"-\x-\`-\--\z-\*-\?-')
 c\
 EOF4
 	EOF4