h2o: backport backtrace detection

backport patch for backtrace detection in h2o.

This patch solves the issue of uclibc pretending to be glibc

Signed-off-by: James Taylor <james@jtaylor.id.au>

libs/h2o/Makefile

@@ -2,7 +2,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=h2o
 PKG_VERSION:=2.2.6
-PKG_RELEASE:=2
+PKG_RELEASE:=3
 
 PKG_SOURCE_URL:=https://codeload.github.com/h2o/h2o/tar.gz/v${PKG_VERSION}?
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz

libs/h2o/patches/400-backtrace-detection.patch

@@ -0,0 +1,74 @@
+From 03dbd6757d043581b5d250107b6f1cda6ae203a9 Mon Sep 17 00:00:00 2001
+From: Frederik Deweerdt <fdeweerdt@fastly.com>
+Date: Wed, 25 Oct 2017 13:52:28 -0700
+Subject: [PATCH] Autodetect backtrace and backtrace_symbols_fd
+
+---
+ CMakeLists.txt | 13 +++++++++++++
+ src/main.c     | 10 ++++++----
+ 2 files changed, 19 insertions(+), 4 deletions(-)
+
+diff --git a/CMakeLists.txt b/CMakeLists.txt
+index abfab1f19..2a26fb98a 100644
+--- a/CMakeLists.txt
++++ b/CMakeLists.txt
+@@ -58,6 +58,19 @@ __sync_add_and_fetch(&a, 1);
+ return 0;
+ }" ARCH_SUPPORTS_64BIT_ATOMICS)
+ 
++CHECK_C_SOURCE_COMPILES("
++#include <execinfo.h>
++int main(void) {
++void *p[10];
++int ret = backtrace(p, 10);
++backtrace_symbols_fd(p, ret, 2);
++return 0;
++}" LIBC_HAS_BACKTRACE)
++
++IF (LIBC_HAS_BACKTRACE)
++    ADD_DEFINITIONS("-DLIBC_HAS_BACKTRACE")
++ENDIF ()
++
+ SET(WITH_BUNDLED_SSL_DEFAULT "ON")
+ IF ((NOT UNIX) OR CYGWIN)
+     SET(WITH_BUNDLED_SSL_DEFAULT "OFF")
+diff --git a/src/main.c b/src/main.c
+index 7c346af18..edc7d5eb3 100644
+--- a/src/main.c
++++ b/src/main.c
+@@ -48,7 +48,7 @@
+ #include <openssl/crypto.h>
+ #include <openssl/err.h>
+ #include <openssl/ssl.h>
+-#ifdef __GLIBC__
++#ifdef LIBC_HAS_BACKTRACE
+ #include <execinfo.h>
+ #endif
+ #if H2O_USE_PICOTLS
+@@ -1435,7 +1435,8 @@ static void on_sigterm(int signo)
+     notify_all_threads();
+ }
+ 
+-#ifdef __GLIBC__
++#ifdef LIBC_HAS_BACKTRACE
++
+ static int popen_crash_handler(void)
+ {
+     char *cmd_fullpath = h2o_configurator_get_cmd_path(conf.crash_handler), *argv[] = {cmd_fullpath, NULL};
+@@ -1487,13 +1488,14 @@ static void on_sigfatal(int signo)
+ 
+     raise(signo);
+ }
+-#endif
++
++#endif /* LIBC_HAS_BACKTRACE */
+ 
+ static void setup_signal_handlers(void)
+ {
+     h2o_set_signal_handler(SIGTERM, on_sigterm);
+     h2o_set_signal_handler(SIGPIPE, SIG_IGN);
+-#ifdef __GLIBC__
++#ifdef LIBC_HAS_BACKTRACE
+     if ((crash_handler_fd = popen_crash_handler()) == -1)
+         crash_handler_fd = 2;
+     h2o_set_signal_handler(SIGABRT, on_sigfatal);