Added new class for curl share handle

Added new class for curl share handle.
And, paired the curl handle(S3fsCurl) with the worker thread.
Changed that each thread has its own SSL session cache to prevent data
races.
So OpenSSL suppression for ThreadSanitizer is no longer necessary, so
reverted it.

.github/workflows/ci.yml

@@ -246,7 +246,7 @@ jobs:
             elif [ "${{ matrix.checktype }}" = "sanitize_thread" ]; then
                 echo 'CXX=clang++'
                 echo "CXXFLAGS=${COMMON_CXXFLAGS} -O0 -fsanitize=thread"
-                echo 'TSAN_OPTIONS=halt_on_error=1,suppressions=threadsanitizer_suppressions.txt'
+                echo 'TSAN_OPTIONS=halt_on_error=1'
                 # [NOTE]
                 # Set this to avoid following error when running configure.
                 # "FATAL: ThreadSanitizer: unexpected memory mapping"
@@ -269,7 +269,7 @@ jobs:
       - name: Build
         run: |
           ./autogen.sh
-          /bin/sh -c "CXX=${CXX} CXXFLAGS=\"${CXXFLAGS}\" LDFLAGS=\"${LDFLAGS}\" TSAN_OPTIONS=\"\" ./configure --prefix=/usr --with-openssl"
+          /bin/sh -c "CXX=${CXX} CXXFLAGS=\"${CXXFLAGS}\" LDFLAGS=\"${LDFLAGS}\" ./configure --prefix=/usr --with-openssl"
           make
 
       - name: Test suite