www/firefox: unbreak on powerpc64, sparc64

In file included from toolkit/crashreporter/google-breakpad/src/third_party/curl/curl.h:44:0,

from toolkit/components/telemetry/pingsender/pingsender_unix_common.cpp:13,
from objdir/toolkit/components/telemetry/pingsender/Unified_cpp_pingsender0.cpp:11:

toolkit/crashreporter/google-breakpad/src/third_party/curl/curlrules.h:144:41: error: size of array 'curl_rule_01' is negative

[CurlchkszEQ(long, CURL_SIZEOF_LONG)];
                                    ^

Reported by: jhibbits