Implement async termination of blocking thread (#2516)

Send a signal whose handler is no-op to a blocking thread to wake up
the blocking syscall with either EINTR equivalent or partial success.

Unlike the approach taken in the `dev/interrupt_block_insn` branch (that is,
signal + longjmp similarly to `OS_ENABLE_HW_BOUND_CHECK`), this PR
does not use longjmp because:
* longjmp from signal handler doesn't work on nuttx
  refer to https://github.com/apache/nuttx/issues/10326
* the singal+longjmp approach may be too difficult for average programmers
  who might implement host functions to deal with

See also https://github.com/bytecodealliance/wasm-micro-runtime/issues/1910

core/iwasm/common/wasm_suspend_flags.h

@@ -20,6 +20,8 @@ extern "C" {
 #define WASM_SUSPEND_FLAG_BREAKPOINT 0x4
 /* Return from pthread_exit */
 #define WASM_SUSPEND_FLAG_EXIT 0x8
+/* The thread might be blocking */
+#define WASM_SUSPEND_FLAG_BLOCKING 0x10
 
 typedef union WASMSuspendFlags {
     bh_atomic_32_t flags;