Revert removal of unreadCh change for performance

Turns out unreadCh is much more efficient than seek(-1, SEEK_CUR).
Update comments and code to reflect this.

1 files changed, 1 insertions, 1 deletions

diff --git a/libqpdf/FileInputSource.cc b/libqpdf/FileInputSource.cc
index 5ec6a170..cd8feda4 100644
--- a/libqpdf/FileInputSource.cc
+++ b/libqpdf/FileInputSource.cc
@@ -80,7 +80,7 @@ FileInputSource::findAndSkipNextEOL()
                     }
                     else if (! ((ch == '\r') || (ch == '\n')))
                     {
-                        this->seek(-1, SEEK_CUR);
+                        this->unreadCh(ch);
                         done = true;
                     }
                 }