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

tests/libtest/test.h

@@ -20,14 +20,14 @@
  *
  ***************************************************************************/
 
-/* Now include the curl_setup.h file from libcurl's private libdir (the
-   source version, but that might include "curl_config.h" from the build
-   dir so we need both of them in the include path), so that we get good
-   in-depth knowledge about the system we're building this on */
+/* Now include the setup.h file from libcurl's private libdir (the source
+   version, but that might include "curl_config.h" from the build dir so we
+   need both of them in the include path), so that we get good in-depth
+   knowledge about the system we're building this on */
 
 #define CURL_NO_OLDIES
 
-#include "curl_setup.h"
+#include "setup.h"
 
 #include <curl/curl.h>
 
@@ -37,7 +37,7 @@
 #endif
 
 #ifdef TPF
-#  include "curl_select.h"
+#  include "select.h"
 #endif
 
 #define test_setopt(A,B,C) \