Remove unnecessary trailing whitespace

Trim trailing whitespace. It doesn't match OpenSSL coding standards,
AFAICT, and it can cause problems with git tooling.

Trailing whitespace remains in test data and external source.

Reviewed-by: Kurt Roeckx <kurt@roeckx.be>
Reviewed-by: Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/8092)

Configurations/README

diff --git a/Configurations/README b/Configurations/README
index 1e4d545..a106f8c 100644
--- a/Configurations/README
+++ b/Configurations/README
@@ -118,7 +118,7 @@
                            '<unistd.h>'.  This is very rarely needed.
 
         shared_extension => File name extension used for shared
-                            libraries. 
+                            libraries.
         obj_extension   => File name extension used for object files.
                            On unix, this defaults to ".o" (NOTE: this
                            is here for future use, it's not