Document OPENSSL_VERSION_NUMBER

doc/crypto/OPENSSL_VERSION_NUMBER.pod

+=pod
+
+=head1 NAME
+
+OPENSSL_VERSION_NUMBER, SSLeay - Get OpenSSL version number
+
+=head1 SYNOPSIS
+
+ #include <openssl/opensslv.h>
+ #define OPENSSL_VERSION_NUMBER 0xnnnnnnnnnL
+
+ #include <openssl/crypto.h>
+ long SSLeay(void);
+
+=head1 DESCRIPTION
+
+OPENSSL_VERSION_NUMBER is a numeric release version identifier:
+
+ MMNNFFRBB major minor fix final beta/patch
+
+for example
+
+ 0x000904100 == 0.9.4 release
+ 0x000905000 == 0.9.5 dev
+
+Versions prior to 0.9.3 have identifiers E<lt> 0x0930.
+For backward compatibility, SSLEAY_VERSION_NUMBER is also defined.
+
+SSLeay() returns this number. The return value can be compared to the
+macro to make sure that the correct version of the library has been
+loaded, especially when using DLLs on Windows systems.
+
+=head1 RETURN VALUE
+
+The version number.
+
+=head1 SEE ALSO
+
+L<crypto(3)|crypto(3)>
+
+=head1 HISTORY
+
+SSLeay() and SSLEAY_VERSION_NUMBER are available in all versions of SSLeay and OpenSSL.
+OPENSSL_VERSION_NUMBER is available in all versions of OpenSSL.
+
+=cut