Add C backtrace on Linux.

backtrace.c

@@ -0,0 +1,15 @@
+#include <execinfo.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+int main()
+{
+    int nptrs;
+#define BACKTRACE_SIZE 128
+    void *buffer[BACKTRACE_SIZE];
+    nptrs = backtrace(buffer, BACKTRACE_SIZE);
+    printf("backtrace() returned %d addresses\n", nptrs);
+    backtrace_symbols_fd(buffer, nptrs, 1);
+}
+