Revert changes relative to lib/*.[ch] recent renaming

This reverts renaming and usage of lib/*.h header files done
28-12-2012, reverting 2 commits:

  f871de0... build: make use of 76 lib/*.h renamed files
  ffd8e12... build: rename 76 lib/*.h files

This also reverts removal of redundant include guard (redundant thanks
to changes in above commits) done 2-12-2013, reverting 1 commit:

  c087374... curl_setup.h: remove redundant include guard

This also reverts renaming and usage of lib/*.c source files done
3-12-2013, reverting 3 commits:

  13606bb... build: make use of 93 lib/*.c renamed files
  5b6e792... build: rename 93 lib/*.c files
  7d83dff... build: commit 13606bbfde follow-up 1

Start of related discussion thread:

  http://curl.haxx.se/mail/lib-2013-01/0012.html

Asking for confirmation on pushing this revertion commit:

  http://curl.haxx.se/mail/lib-2013-01/0048.html

Confirmation summary:

  http://curl.haxx.se/mail/lib-2013-01/0079.html

NOTICE: The list of 2 files that have been modified by other
intermixed commits, while renamed, and also by at least one
of the 6 commits this one reverts follows below. These 2 files
will exhibit a hole in history unless git's '--follow' option
is used when viewing logs.

  lib/curl_imap.h
  lib/curl_smtp.h

1 files changed, 58 insertions, 0 deletions

diff --git a/lib/timeval.h b/lib/timeval.h
new file mode 100644
index 000000000..b464ae406
--- /dev/null
+++ b/lib/timeval.h
@@ -0,0 +1,58 @@
+#ifndef HEADER_CURL_TIMEVAL_H
+#define HEADER_CURL_TIMEVAL_H
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 1998 - 2007, Daniel Stenberg, <daniel@haxx.se>, et al.
+ *
+ * This software is licensed as described in the file COPYING, which
+ * you should have received as part of this distribution. The terms
+ * are also available at http://curl.haxx.se/docs/copyright.html.
+ *
+ * You may opt to use, copy, modify, merge, publish, distribute and/or sell
+ * copies of the Software, and permit persons to whom the Software is
+ * furnished to do so, under the terms of the COPYING file.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ***************************************************************************/
+
+/*
+ * CAUTION: this header is designed to work when included by the app-side
+ * as well as the library. Do not mix with library internals!
+ */
+
+#include "setup.h"
+
+struct timeval curlx_tvnow(void);
+
+/*
+ * Make sure that the first argument (t1) is the more recent time and t2 is
+ * the older time, as otherwise you get a weird negative time-diff back...
+ *
+ * Returns: the time difference in number of milliseconds.
+ */
+long curlx_tvdiff(struct timeval t1, struct timeval t2);
+
+/*
+ * Same as curlx_tvdiff but with full usec resolution.
+ *
+ * Returns: the time difference in seconds with subsecond resolution.
+ */
+double curlx_tvdiff_secs(struct timeval t1, struct timeval t2);
+
+long Curl_tvlong(struct timeval t1);
+
+/* These two defines below exist to provide the older API for library
+   internals only. */
+#define Curl_tvnow() curlx_tvnow()
+#define Curl_tvdiff(x,y) curlx_tvdiff(x,y)
+#define Curl_tvdiff_secs(x,y) curlx_tvdiff_secs(x,y)
+
+#endif /* HEADER_CURL_TIMEVAL_H */
+