[PATCH] build fix regression on systems without nss

[Victor Kamensky]

After "eb3896ef0 Add the capability to list http servers." and
"3580be162 Move the code getting a certificate from a server into each backend."
commits on a system where nss-devel is not installed or one build
systemtap with --without-nss configure option, build fails with the
following compilation error:

> make[2]: Entering directory '/home/wd8/systemtap/20180306/build'
>   CXX      stap-main.o
> In file included from ../systemtap/main.cxx:24:0:
> ../systemtap/csclient.h:41:37: error: ‘compile_server_info’ has not been declared
>    virtual void fill_in_server_info (compile_server_info &info) = 0;
>                                     ^~~~~~~~~~~~~~~~~~~

Fix is simple add '#if HAVE_NSS' check around new code.

Signed-off-by: Victor Kamensky <kamensky@cisco.com>
---
 csclient.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/csclient.h b/csclient.h
index c2518ae95..5128aea41 100644
--- a/csclient.h
+++ b/csclient.h
@@ -38,8 +38,10 @@ public:
   virtual void add_mok_fingerprint(const std::string &fingerprint) = 0;
   virtual int finalize_mok_fingerprints() = 0;
 
+#if HAVE_NSS
   virtual void fill_in_server_info (compile_server_info &info) = 0;
   virtual int trust_server_info (const compile_server_info &info) = 0;
+#endif
 
   std::string server_tmpdir;
   cs_protocol_version server_version;
-- 
2.14.3