Build fails looking for execinfo.h when building against musl

[James-TR]

execinfo.h is a GNU specific header, and doesn't exist under musl.

A suggestion would be to make it so this feature is auto-detected to exist, and even add a configure flag.

Relevant log entry:

x86_64-gentoo-linux-musl-g++ -DHAVE_CONFIG_H -I. -I..   -pthread     -I.. -I.. -DSYSCONFDIR=\"/etc/powerdns\" -DPKGLIBDIR=\"/usr/lib/powerdns/pdns\" -DLOCALSTATEDIR=\"/var/run\" -pthread    -I../pdns/ext/rapidjson/include -I../pdns/ext/yahttp -D_GNU_SOURCE -march=native -O2 -fstack-protector-all -fomit-frame-pointer -fstack-protector --param ssp-buffer-size=4 -fPIE -DPIE -c -o receiver.o receiver.cc
receiver.cc:377:22: fatal error: execinfo.h: No such file or directory
 #include <execinfo.h>
                      ^

[James-TR]

pdns/pdns/receiver.cc

Lines 376 to 397 in 201464d

	#ifdef __linux__
	#include <execinfo.h>
	static void tbhandler(int num)
	{
	L<<Logger::Critical<<"Got a signal "<<num<<", attempting to print trace: "<<endl;
	void *array[20]; //only care about last 17 functions (3 taken with tracing support)
	size_t size;
	char **strings;
	size_t i;
	size = backtrace (array, 20);
	strings = backtrace_symbols (array, size); //Need -rdynamic gcc (linker) flag for this to work
	for (i = 0; i < size; i++) //skip useless functions
	L<<Logger::Error<<strings[i]<<endl;
	signal(SIGABRT, SIG_DFL);
	abort();//hopefully will give core
	}
	#endif

appears to be the offending lines of code. You can't rely on Linux to only use glibc.

[Habbie]

Fixed by merge of #1958