linux: Fix implicit conversion error on ARM (see https://crbug.com/1292951#c100)

patch/patch.cfg

@@ -591,5 +591,11 @@ patches = [
     # https://bitbucket.org/chromiumembedded/cef/issues/3314
     # Also reverts the changes from https://crrev.com/db245883e1
     'name': 'linux_printing_context',
+  },
+  {
+    # Linux: Fix implicit conversion error on ARM.
+    # https://chromium-review.googlesource.com/c/linux-syscall-support/+/3786946/
+    'name': 'linux_arm_1292951',
+    'path': 'third_party/lss',
   }
 ]

patch/patches/linux_arm_1292951.patch

@@ -0,0 +1,18 @@
+diff --git linux_syscall_support.h linux_syscall_support.h
+index e4e816f..bbbd338 100644
+--- linux_syscall_support.h
++++ linux_syscall_support.h
+@@ -4861,7 +4861,12 @@ struct kernel_statfs {
+                                           size_t count, loff_t off) {
+       union { loff_t off; unsigned arg[2]; } o = { off };
+       return LSS_NAME(_pwrite64)(fd, buf, count,
+-                                 LSS_LLARG_PAD o.arg[0], o.arg[1]);
++                                 LSS_LLARG_PAD o.arg[0],
++#if !defined(__ARM_EABI__) && !defined(__mips__)
++                                 static_cast<long>(o.arg[1]));
++#else
++                                 o.arg[1]);
++#endif
+     }
+     LSS_INLINE int LSS_NAME(readahead)(int fd, loff_t off, size_t count) {
+       union { loff_t off; unsigned arg[2]; } o = { off };