Fix compile for Linux 32b fuzz target

This code was previously not enabled, but was turned on recently.
However, there's no CQ check for 32 bit code.

Bug: chromium:966292
Change-Id: I4a3205d8517575e25d3e525f247ad45a906c3e25
Reviewed-on: https://chromium-review.googlesource.com/c/crashpad/crashpad/+/1627679
Reviewed-by: Joshua Peraza <jperaza@chromium.org>
Commit-Queue: Scott Graham <scottmg@chromium.org>
diff --git a/snapshot/elf/elf_image_reader_fuzzer.cc b/snapshot/elf/elf_image_reader_fuzzer.cc
index 73bded7..4b9fcb0 100644
--- a/snapshot/elf/elf_image_reader_fuzzer.cc
+++ b/snapshot/elf/elf_image_reader_fuzzer.cc
@@ -31,7 +31,8 @@
     VMAddress offset_in_data = address - fake_base_;
     if (offset_in_data > size_)
       return -1;
-    ssize_t read_size = std::min(size_ - offset_in_data, size);
+    size_t read_size =
+        std::min(static_cast<size_t>(size_ - offset_in_data), size);
     memcpy(buffer, &data_[offset_in_data], read_size);
     return read_size;
   }