minidump-2-core: check platform_id for Linux

We have an enum for the OS, so check that instead.

Change-Id: I4bb38145553e3f5a2aa9baab330d588fef09a07e
Reviewed-on: https://chromium-review.googlesource.com/c/breakpad/breakpad/+/2757679
Reviewed-by: Joshua Peraza <jperaza@chromium.org>

src/tools/linux/md2core/minidump-2-core.cc

@@ -626,8 +626,7 @@ ParseSystemInfo(const Options& options, CrashedProcess* crashinfo,
 #else
 #error "This code has not been ported to your platform yet"
 #endif
-  if (!strstr(full_file.GetAsciiMDString(sysinfo->csd_version_rva).c_str(),
-              "Linux") &&
+  if (sysinfo->platform_id != MD_OS_LINUX &&
       sysinfo->platform_id != MD_OS_NACL) {
     fprintf(stderr, "This minidump was not generated by Linux or NaCl.\n");
     exit(1);