[PATCH] Don't call modperl_threaded_mpm() et al. from XS code

r594345 (and later r1241983 and r1245916, all merged into trunk with
r1602105) modified modperl_trace() to call functions that are provided
by mod_perl.c. However, the same code is compiled into the APR XS module
without mod_perl.o linkage, so we end up with missing symbols in APR.so.

% objdump -T blib/arch/auto/APR/APR.so|grep UND|grep modperl
0000000000000000      D  *UND*  0000000000000000              modperl_is_running
0000000000000000      D  *UND*  0000000000000000              modperl_threaded_mpm
0000000000000000      D  *UND*  0000000000000000              modperl_threads_started

For the most part these missing symbols don't matter when modperl_trace()
doesn't actually get called, but CPAN modules like Apache-Gallery that
use APR and run their suites with PERL_DL_NONLAZY=1 now fail their tests
because of this.

Guard the problematic invocations with #ifndef MP_IN_XS, which is
defined for the XS module builds.

Bug-Debian: https://bugs.debian.org/765174
---
 src/modules/perl/modperl_common_log.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/modules/perl/modperl_common_log.c b/src/modules/perl/modperl_common_log.c
index 3335257..3bdb359 100644
--- a/src/modules/perl/modperl_common_log.c
+++ b/src/modules/perl/modperl_common_log.c
@@ -53,6 +53,7 @@ void modperl_trace(const char *func, const char *fmt, ...)
        http://apr.apache.org/docs/apr/1.4/group__apr__lib.html#gad2cd3594aeaafd45931d1034965f48c1
      */
 
+#ifndef MP_IN_XS
     /* PERL_GET_CONTEXT yields nonsense until the first interpreter is
      * created. Hence the modperl_is_running() question. */
     if (modperl_threaded_mpm()) {
@@ -77,6 +78,7 @@ void modperl_trace(const char *func, const char *fmt, ...)
         apr_file_printf(logfile, "[pid=%lu] ", (unsigned long)getpid());
 #endif
     }
+#endif
 
     if (func && *func) {
         apr_file_printf(logfile, "%s: ", func);
-- 
2.1.1