Split command into process and adb

The process API provides the system-specific implementation, the adb API
uses it to expose adb commands.

app/src/util/process.c

@@ -0,0 +1,21 @@
+#include "process.h"
+
+#include "log.h"
+
+bool
+process_check_success(process_t proc, const char *name) {
+    if (proc == PROCESS_NONE) {
+        LOGE("Could not execute \"%s\"", name);
+        return false;
+    }
+    exit_code_t exit_code;
+    if (!process_simple_wait(proc, &exit_code)) {
+        if (exit_code != NO_EXIT_CODE) {
+            LOGE("\"%s\" returned with value %" PRIexitcode, name, exit_code);
+        } else {
+            LOGE("\"%s\" exited unexpectedly", name);
+        }
+        return false;
+    }
+    return true;
+}