Fixed capabilities version.

Previously, capset(2) was called with the 64-bit capabilities version
_LINUX_CAPABILITY_VERSION_3.  With this version Linux kernel expected two
copies of struct __user_cap_data_struct, while only one was submitted.  As a
result, random stack memory was accessed and random capabilities were requested
by the worker.  This sometimes caused capset() errors.  Now the 32-bit version
_LINUX_CAPABILITY_VERSION_1 is used instead.  This is OK since CAP_NET_RAW is
a 32-bit capability (CAP_NET_RAW = 13).

auto/os/linux

diff --git a/auto/os/linux b/auto/os/linux
index 135280f..2c8a9bb 100644
--- a/auto/os/linux
+++ b/auto/os/linux
@@ -181,7 +181,7 @@
 ngx_feature_test="struct __user_cap_data_struct    data;
                   struct __user_cap_header_struct  header;
 
-                  header.version = _LINUX_CAPABILITY_VERSION_3;
+                  header.version = _LINUX_CAPABILITY_VERSION_1;
                   data.effective = CAP_TO_MASK(CAP_NET_RAW);
                   data.permitted = 0;
 

src/os/unix/ngx_process_cycle.c

diff --git a/src/os/unix/ngx_process_cycle.c b/src/os/unix/ngx_process_cycle.c
index 9b0e042..5817a2c 100644
--- a/src/os/unix/ngx_process_cycle.c
+++ b/src/os/unix/ngx_process_cycle.c
@@ -865,7 +865,7 @@
             ngx_memzero(&header, sizeof(struct __user_cap_header_struct));
             ngx_memzero(&data, sizeof(struct __user_cap_data_struct));
 
-            header.version = _LINUX_CAPABILITY_VERSION_3;
+            header.version = _LINUX_CAPABILITY_VERSION_1;
             data.effective = CAP_TO_MASK(CAP_NET_RAW);
             data.permitted = data.effective;