NOTES.UNIX: add "Linking your application" paragraph

 Every Unix system has its own set of default locations for shared

 libraries, such as /lib, /usr/lib or possibly /usr/local/lib.  If

 libraries are installed in non-default locations, dynamically linked

 binaries will not find them and therefore fail to run unless they get a

 bit of help from a defined runtime shared library search path.

 binaries will not find them and therefore fail to run, unless they get

 a bit of help from a defined runtime shared library search path.

 For OpenSSL's application (the 'openssl' command), our configuration

 scripts do NOT generally set the runtime shared library search path for

 you.  It's therefore advisable to set it explicitly when configuring

 you.  It's therefore advisable to set it explicitly when configuring,

 unless the libraries are to be installed in directories that you know

 to be in the default list.

 Possible options to set the runtime shared library search path include

 the following:

    -Wl,-rpath,/whatever/path

    -R /whatever/path

    -rpath /whatever/path

    -Wl,-rpath,/whatever/path	# Linux, *BSD, etc.

    -R /whatever/path		# Solaris

    -Wl,-R,/whatever/path	# AIX (-bsvr4 is passed internally)

    -Wl,+b,/whatever/path	# HP-UX

    -rpath /whatever/path	# Tru64, IRIX

 OpenSSL's configuration scripts recognise all these options and pass

 them to the Makefile that they build.  (In fact, it recognises anything

 starting with '-Wl,' as a linker option, so for example, HP-UX'

 '-Wl,+b,/whatever/path' would be used correctly)

 them to the Makefile that they build. (In fact, all arguments starting

 with '-Wl,' are recognised as linker options.)

 Please do not use verbatim directories in your runtime shared library

 search path!  Some OpenSSL config targets add an extra directory level

    $ ./config --prefix=/usr/local/ssl --openssldir=/usr/local/ssl \

        '-Wl,--enable-new-dtags,-rpath,$(LIBRPATH)'

 It might be worth noting that some/most ELF systems implement support

 for runtime search path relative to the directory containing current

 executable, by interpreting $ORIGIN along with some other internal

 variables. Consult your system documentation.

 Linking your application

 ------------------------

 Third-party applications dynamically linked with OpenSSL (or any other)

 shared library face exactly the same problem with non-default locations.

 The OpenSSL config options mentioned above might or might not have bearing

 on linking of the target application. "Might" means that under some

 circumstances it would be sufficient to link with OpenSSL shared library

 "naturally", i.e. with -L/whatever/path -lssl -lcrypto. But there are

 also cases when you'd have to explicitly specify runtime search path

 when linking your application. Consult your system documentation and use

 above section as inspiration...

 Shared OpenSSL builds also install static libraries. Linking with the

 latter is likely to require special care, because linkers usually look

 for shared libraries first and tend to remain "blind" to static OpenSSL

 libraries. Referring to system documentation would suffice, if not for

 a corner case. On AIX static libraries (in shared build) are named

 differently, add _a suffix to link with them, e.g. -lcrypto_a.