jitter: add a new provider containing a jitter entropy source alone

This entropy source can be used instead of SEED-SRC. Sample
openssl.cnf configuration is provided. It is built as a separate
provider, because it is likely to require less frequent updates than
fips provider. The same build likely can span multiple generations of
FIPS 140 standard revisions.

Note that rand-instances currently chain from public/private instances
to primary, prior to consuming the seed. Thus currently a unique ESV
needs to be obtained, and resue of jitterentropy.a certificate is not
possible as is. Separately a patch will be sent to allow for
unchaining public/private RAND instances for the purpose of reusing
ESV.

Also I do wonder if it makes sense to create a fips variant of stock
SEED-SRC entropy source, which in addition to using getrandom() also
verifies that the kernel is operating in FIPS mode and thus is likely
a validated entropy source. As in on Linux, check that
/proc/sys/crypto/fips_enabled is set to 1, and similar checks on
Windows / MacOS and so on.

Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/24844)

Configure

@@ -476,6 +476,7 @@ my @disablables = (
     "gost",
     "http",
     "idea",
+    "jitter",
     "ktls",
     "legacy",
     "loadereng",
@@ -586,6 +587,7 @@ our %disabled = ( # "what"         => "comment"
                   "fuzz-afl"            => "default",
                   "fuzz-libfuzzer"      => "default",
                   "pie"                 => "default",
+                  "jitter"              => "default",
                   "ktls"                => "default",
                   "md2"                 => "default",
                   "msan"                => "default",
@@ -1019,6 +1021,14 @@ while (@argvcopy)
                         {
                         $config{openssldir}=$1;
                         }
+                elsif (/^--with-jitter-include=(.*)$/)
+                        {
+                        $withargs{jitter_include}=$1;
+                        }
+                elsif (/^--with-jitter-lib=(.*)$/)
+                        {
+                        $withargs{jitter_lib}=$1;
+                        }
                 elsif (/^--with-zlib-lib=(.*)$/)
                         {
                         $withargs{zlib_lib}=$1;