FindOpenSSL: Report crypto and ssl libraries separately

Some applications only need the OpenSSL crypto library and want to avoid
linking against the SSL library.  Set OPENSSL_CRYPTO_LIBRARY and
OPENSSL_SSL_LIBRARY in the code paths that do not need to find them
separately, and document them publicly.  This allows applications to be
more specific when linking against OpenSSL.
FindOpenGL: Drop explicit dependency on X11 (#15268)

In commit 079e8469ab (... OpenGL always needs X11 on Unix, 2002-09-05)
the FindOpenGL module was taught to search for X11 as a dependency of
the OpenGL library.  This was done without a detailed explanation, and
the dependency should not be explicitly needed because OpenGL headers
should not expose applications to X11 APIs directly.

Unfortunately the only way to know if anything legitimately depends on
this behavior (perhaps in static library cases) is to simply remove it
and wait for issues to be reported.  If so, then we can add some kind of
compatibility setting for this later.  Add a release note to draw
attention to this change.

Reported-by: Dainius "GreatEmerald" Masiliūnas <pastas4@gmail.com>
CMakeParseImplicitLinkInfo: Fix implicit library logging

In commit v3.1.0-rc1~640^2~5 (Clean up usage of if(... MATCHES regex)
followed string(REGEX REPLACE regex), 2014-04-06) we accidentally broke
logging of the implicit library detection.  Restore use of the
intermediate 'lib' variable so that the log message is constructed
properly.

Reported-by: Bill Somerville <bill@classdesign.com>
Makefile: Do not create an empty linker response file

Since commit v3.1.0-rc1~821^2 (Windows: Use response files to specify
link libraries for GNU tools, 2014-03-04) we use a response file to pass
possibly long linker flag lists to the GNU linker on Windows.  On MinGW,
this may cause gfortran to use a response file to pass some flags to its
own internal invocation.  This is okay except when we are parsing
implicit link flags from the compiler ABI detection build.  If gfortran
uses a response file in that case then we may miss extracting some of
the implicit link flags, such as -lgfortran.  Fortunately, in the
compiler ABI detection case we do not actually link to anything so the
response file is empty.  Work around this problem by simply not using a
response file when the list of flags it is used to pass is empty (or
just whitespace).

Reported-by: Bill Somerville <bill@classdesign.com>
Merge branch 'fix-implicit-lib-logging' into release
Merge branch 'link-no-empty-response-files' into release
Help: Fix typo in cmake-compile-features(7) manual

Fix spelling 'execptions' => 'exceptions'.
Merge topic 'FindOpenSSL-separate-libs'

be9bec5d FindOpenSSL: Report crypto and ssl libraries separately
Merge topic 'link-no-empty-response-files'

1c5be1f3 Makefile: Do not create an empty linker response file
Merge topic 'fix-implicit-lib-logging'

20bf6971 CMakeParseImplicitLinkInfo: Fix implicit library logging
Merge topic 'doc-compile-features-typo'

64f8c533 Help: Fix typo in cmake-compile-features(7) manual
Merge topic 'FindOpenGL-no-X11'

d051cbda FindOpenGL: Drop explicit dependency on X11 (#15268)
Merge branch 'doc-compile-features-typo' into release
Merge branch 'release'