Make intr optional for adb commands

All adb commands are executed with an "interruptor", so that they can be
interrupted on Ctrl+C.

Make this interruptor optional, so that we could call "adb kill-server"
in OTG mode. This command always returns almost immediately anyway.

Ideally, we should make all blocking calls interruptible (including
libusb calls, by using the asynchronous API), but it's a lot of work,
and in practice it works well enough.

PR #3011 <https://github.com/Genymobile/scrcpy/pull/3011>

app/src/adb/adb.c

@@ -150,7 +150,7 @@ process_check_success_internal(sc_pid pid, const char *name, bool close,
 static bool
 process_check_success_intr(struct sc_intr *intr, sc_pid pid, const char *name,
                            unsigned flags) {
-    if (!sc_intr_set_process(intr, pid)) {
+    if (intr && !sc_intr_set_process(intr, pid)) {
         // Already interrupted
         return false;
     }
@@ -158,7 +158,9 @@ process_check_success_intr(struct sc_intr *intr, sc_pid pid, const char *name,
     // Always pass close=false, interrupting would be racy otherwise
     bool ret = process_check_success_internal(pid, name, false, flags);
 
-    sc_intr_set_process(intr, SC_PROCESS_NONE);
+    if (intr) {
+        sc_intr_set_process(intr, SC_PROCESS_NONE);
+    }
 
     // Close separately
     sc_process_close(pid);

app/src/util/process_intr.c

@@ -3,27 +3,33 @@
 ssize_t
 sc_pipe_read_intr(struct sc_intr *intr, sc_pid pid, sc_pipe pipe, char *data,
                   size_t len) {
-    if (!sc_intr_set_process(intr, pid)) {
+    if (intr && !sc_intr_set_process(intr, pid)) {
         // Already interrupted
         return false;
     }
 
     ssize_t ret = sc_pipe_read(pipe, data, len);
 
-    sc_intr_set_process(intr, SC_PROCESS_NONE);
+    if (intr) {
+        sc_intr_set_process(intr, SC_PROCESS_NONE);
+    }
+
     return ret;
 }
 
 ssize_t
 sc_pipe_read_all_intr(struct sc_intr *intr, sc_pid pid, sc_pipe pipe,
                       char *data, size_t len) {
-    if (!sc_intr_set_process(intr, pid)) {
+    if (intr && !sc_intr_set_process(intr, pid)) {
         // Already interrupted
         return false;
     }
 
     ssize_t ret = sc_pipe_read_all(pipe, data, len);
 
-    sc_intr_set_process(intr, SC_PROCESS_NONE);
+    if (intr) {
+        sc_intr_set_process(intr, SC_PROCESS_NONE);
+    }
+
     return ret;
 }