[pcl::io::loadPCDFile] The issue of thread stopping

Occasionally, there may be thread jamming issues when reading a PCD file.

The following is the stack information when the thread stops:
#0 0x0000ffff98218b44 in std::istream::sentry::sentry(std::istream&, bool) () from /lib/aarch64-linux-gnu/libstdc++.so.6
#1 0x0000ffff981c4420 in std::basic_istream<char, std::char_traits >& std::getline<char, std::char_traits, std::allocator >(std::basic_istream<char, std::char_traits >&, std::__cxx11::basic_string<char, std::char_traits, std::allocator >&, char) () from /lib/aarch64-linux-gnu/libstdc++.so.6
#2 0x0000ffff742e1798 in pcl::PCDReader::readHeader(std::istream&, pcl::PCLPointCloud2&, Eigen::Matrix<float, 4, 1, 0, 4, 1>&, Eigen::Quaternion<float, 0>&, int&, int&, unsigned int&) () from /lib/aarch64-linux-gnu/libpcl_io.so.1.10
#3 0x0000ffff742e31a4 in pcl::PCDReader::readHeader(std::__cxx11::basic_string<char, std::char_traits, std::allocator > const&, pcl::PCLPointCloud2&, Eigen::Matrix<float, 4, 1, 0, 4, 1>&, Eigen::Quaternion<float, 0>&, int&, int&, unsigned int&, int) () from /lib/aarch64-linux-gnu/libpcl_io.so.1.10
#4 0x0000ffff742e0ea8 in pcl::PCDReader::read(std::__cxx11::basic_string<char, std::char_traits, std::allocator > const&, pcl::PCLPointCloud2&, Eigen::Matrix<float, 4, 1, 0, 4, 1>&, Eigen::Quaternion<float, 0>&, int&, int) () from /lib/aarch64-linux-gnu/libpcl_io.so.1.10
#7 0x0000ffff981d7f9c in ?? () from /lib/aarch64-linux-gnu/libstdc++.so.6
#8 0x0000ffff98c51624 in start_thread () from /lib/aarch64-linux-gnu/libpthread.so.0
#9 0x0000ffff9804562c in ?? () from /lib/aarch64-linux-gnu/libc.so.6

Start with the PCLReader::readHeader(std::istream&) and PCLReader::read call chain shown in the stack trace, then reproduce the reported PCD loading scenario. Compare the blocked stream state with the surrounding PCD parsing flow; done means the cause of the thread stop is identified and PCD loading no longer hangs in that scenario.