Fix more CRLF injection problems

Fix more CRLF injection problems.

Bug fixes

• Don't loading system certs from Keychain on iOS (#1546)
• Initialize sockaddr_un to fix valgrind uninitialised byte message. (#1547
• #1547)
• Using set_content_provider with length of 0 makes it infinitely loop #1545
• How to check if server is running successfully in another thread? #1548
• Fix leaked handle in create_socket (#1554)

Bug fixes

• Fix "Location" header url corrupted by percent-unescaping in redirect… #1459
• Trailing headers not handled #1486
• SSL access through a proxy causes SIGSEGV #1533

Some new features and bug fixes

• System certs support on macOS (#1474)
• Add Request::get_file_values method (#1495)
• Fix: assert socket_requests_are_from_thread_ std::this_thread::get_id() (#1498)
• Fix: multipart Content-Type headers with both boundary and charset parameters (#1516)

Update including breaking change

• Removed is_writable() from DataSink (Resolve #1478, too) (#1483) - This is a breaking change.
• add to_human_string (#1467)
• Issue 52666: cpp-httplib:server_fuzzer: Timeout in server_fuzzer

Some updates

• Support LOCAL_ADDR and LOCAL_PORT header in client Request (#1450)
• Add EINTR and EAGAIN judge for accept (#1438)
• Add support for requests with both MultipartFormDataItems and Content Providers (#1454)

Bug fixes

• duration_to_sec_and_usec narrowing #1426
• EXCEPTION_WHAT is not set if exception text contains newlines #1437
• Windows CMake directory install fix #1434
• Post function donnot have the implement which only has path, header #1421
• undef poll at the end if CPPHTTPLIB_USE_POLL #1427
• Get client process id over ip/port when server runs on UNIX socket. #1418
• avoid lockup in ThreadPool::shutdown() on legacy host #1417
• upport compilation on AIX #1402

v0.11.2

• Add multipart form-data for PUT requests. (#1351)
• Issue 49740 in oss-fuzz: cpp-httplib:server_fuzzer: Timeout in server_fuzzer
• build: set soversion to major.minor (#1357)
• Detecting client disconnection (#1373)

Some updates

• Issue 49512: cpp-httplib:server_fuzzer: Timeout in server_fuzzer
• Add socket method to Client (#1341)
• UNIX domain socket support (#1346)

Some breaking changes

• No longer support VS 2013 and older
• Changed to use std::exception_ptr in exception handler
• Changed to use const std::string & as much as possible instead of const char *