WHIP: Fix bugs causing build OpenSSL error, to work with Pion

1. Fix OpenSSL build error.
2. Support OpenSSL 1.0.1k and newer versions.
3. Support WHIP authorization via Bearer HTTP header.
4. Change the option default value from 1500 to 1200, to make Pion work.
5. Detect the minimum required OpenSSL version, should be 1.0.1k and newer.
6. Quickly check the SDP answer by taking a glance at the first few bytes.

configure

@@ -6801,6 +6801,14 @@ enabled rkmpp             && { require_pkg_config rkmpp rockchip_mpp  rockchip/r
                              }
 enabled vapoursynth       && require_pkg_config vapoursynth "vapoursynth-script >= 42" VSScript.h vsscript_init
 
+enabled openssl            && {
+    enabled rtc_muxer && {
+        $pkg_config --exists --print-errors "openssl >= 1.0.1k" ||
+        require_pkg_config openssl "openssl >= 1.0.1k" openssl/ssl.h SSL_library_init ||
+        require_pkg_config openssl "openssl >= 1.0.1k" openssl/ssl.h OPENSSL_init_ssl
+    }
+}
+
 
 if enabled gcrypt; then
     GCRYPT_CONFIG="${cross_prefix}libgcrypt-config"

doc/muxers.texi

@@ -1361,26 +1361,29 @@ This muxer supports the following options:
 
 @table @option
 
-@item ice_arq_max @var{size}
+@item ice_arq_max @var{integer}
 Set the maximum number of retransmissions for the ICE ARQ mechanism.
 Default value is 5.
 
-@item ice_arq_timeout @var{size}
+@item ice_arq_timeout @var{integer}
 Set the start timeout in milliseconds for the ICE ARQ mechanism.
 Default value is 30.
 
-@item dtls_arq_max @var{size}
+@item dtls_arq_max @var{integer}
 Set the maximum number of retransmissions for the DTLS ARQ mechanism.
 Default value is 5.
 
-@item dtls_arq_timeout @var{size}
+@item dtls_arq_timeout @var{integer}
 Set the start timeout in milliseconds for the DTLS ARQ mechanism.
 Default value is 50.
 
-@item pkt_size @var{size}
+@item pkt_size @var{integer}
 Set the maximum size, in bytes, of RTP packets that send out.
 Default value is 1500.
 
+@item authorization @var{string}
+The optional Bearer token for WHIP Authorization.
+
 @end table
 
 @anchor{ico}