[PATCH 4/3] http: gperf 3.0.3 compatibility

[Eric Wong <e@80x24.org>]

gperf actually used to use offsetof in older versions:

  https://git.savannah.gnu.org/cgit/gperf.git/commit?h=b468e3aae05d176d

So we don't need to do that substitution for versions before
that commit in gperf.

Now why do we care about gperf 3.0.3 from 2007?  That's because
FreeBSD is stuck on 3.0.3 from GPL-3-phobia, despite the
gperf manual explicitly stating the output is NOT subject to the
copyright of gperf:

https://www.gnu.org/software/gperf/manual/gperf.html#Output-Copyright

But there's plenty of other GPL-3 packages distributed by FreeBSD...

Fwiw, OpenBSD and NetBSD have no problem with distributing the latest
gperf 3.1; but I haven't tested those systems.
---
 ext/unicorn_http/gperf.rb | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/ext/unicorn_http/gperf.rb b/ext/unicorn_http/gperf.rb
index 9765f86..330f70d 100644
--- a/ext/unicorn_http/gperf.rb
+++ b/ext/unicorn_http/gperf.rb
@@ -9,7 +9,8 @@
   "\nstatic#$&"
 }.
 
-gsub!(
+# gperf 3.0.3 (on FreeBSD 12.0) actually uses offsetof
+gsub(
 # gperf 3.0.x used "(int)(long)", 3.1 uses "(int)(size_t)",
 #  input: {(int)(size_t)&((struct cf_pool_t *)0)->cf_pool_str3},
 # output: {offsetof(struct cf_pool_t, cf_pool_str3)},
-- 
EW