disable webtry seccmp on non-linux build

experimental/webtry/main.cpp

 #include <sys/time.h>
 #include <sys/resource.h>
 
 #include "SkCanvas.h"
 #include "SkCommandLineFlags.h"
 #include "SkData.h"
 #include "SkForceLinking.h"
 #include "SkGraphics.h"
 #include "SkImageDecoder.h"
 #include "SkImageEncoder.h"
 #include "SkImageInfo.h"
 #include "SkStream.h"
 #include "SkSurface.h"
 
 #include "seccomp_bpf.h"
 
 __SK_FORCE_IMAGE_DECODER_LINKING;
 
 DEFINE_string(out, "", "Filename of the PNG to write to.");
 DEFINE_string(source, "", "Filename of the source image.");
 
 // Defined in template.cpp.
 extern SkBitmap source;
 
 static bool install_syscall_filter() {
+
+#ifndef SK_UNSAFE_BUILD_DESKTOP_ONLY
     struct sock_filter filter[] = {
         /* Grab the system call number. */
         EXAMINE_SYSCALL,
         /* List allowed syscalls. */
         ALLOW_SYSCALL(exit_group),
         ALLOW_SYSCALL(exit),
         ALLOW_SYSCALL(fstat),
         ALLOW_SYSCALL(read),
         ALLOW_SYSCALL(write),
         ALLOW_SYSCALL(close),
@@ skipping 21 matching lines @@
         perror("prctl(SECCOMP)");
         goto failed;
     }
     return true;
 
 failed:
     if (errno == EINVAL) {
         fprintf(stderr, "SECCOMP_FILTER is not available. :(\n");
     }
     return false;
+#else
+    return true;
+#endif /* SK_UNSAFE_BUILD_DESKTOP_ONLY */
 }
 
 static void setLimits() {
     struct rlimit n;
 
     // Limit to 5 seconds of CPU.
     n.rlim_cur = 5;
     n.rlim_max = 5;
     if (setrlimit(RLIMIT_CPU, &n)) {
         perror("setrlimit(RLIMIT_CPU)");
@@ skipping 40 matching lines @@
 
     // Write out the image as a PNG.
     SkAutoTUnref<SkImage> image(surface->newImageSnapshot());
     SkAutoTUnref<SkData> data(image->encode(SkImageEncoder::kPNG_Type, 100));
     if (NULL == data.get()) {
         printf("Failed to encode\n");
         exit(1);
     }
     stream.write(data->data(), data->size());
 }