disable webtry seccmp on non-linux build

BUG=skia:
R=jcgregorio@google.com

Author: humper@google.com

Review URL: https://codereview.chromium.org/555993002

experimental/webtry/main.cpp

@@ -23,6 +23,8 @@ DEFINE_string(source, "", "Filename of the source image.");
 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,
@@ -64,6 +66,9 @@ failed:
         fprintf(stderr, "SECCOMP_FILTER is not available. :(\n");
     }
     return false;
+#else
+    return true;
+#endif /* SK_UNSAFE_BUILD_DESKTOP_ONLY */
 }
 
 static void setLimits() {

experimental/webtry/seccomp_bpf.h

@@ -14,6 +14,8 @@
 #ifndef _SECCOMP_BPF_H_
 #define _SECCOMP_BPF_H_
 
+#ifndef SK_UNSAFE_BUILD_DESKTOP_ONLY
+
 #define _GNU_SOURCE 1
 #include <stdio.h>
 #include <stddef.h>
@@ -62,4 +64,6 @@ struct seccomp_data {
 #define KILL_PROCESS \
     BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_KILL)
 
+#endif /* SK_UNSAFE_BUILD_DESKTOP_ONLY */
+
 #endif /* _SECCOMP_BPF_H_ */