Replace variable length array with std::vector in print_stacktrace()

The function does memory allocation from heap anyway, so should not be
a problem to use STL container.

src/app/stacktrace.h

@@ -9,16 +9,18 @@
 #include <execinfo.h>
 #include <cxxabi.h>
 
+#include <vector>
+
 /** Print a demangled stack backtrace of the caller function to FILE* out. */
 static inline void print_stacktrace(FILE *out = stderr, unsigned int max_frames = 63)
 {
     fprintf(out, "stack trace:\n");
 
     // storage array for stack trace address data
-    void *addrlist[max_frames + 1];
+    std::vector<void *> addrlist(max_frames + 1);
 
     // retrieve current stack addresses
-    int addrlen = backtrace(addrlist, sizeof(addrlist) / sizeof(void *));
+    int addrlen = backtrace(addrlist.data(), addrlist.size());
 
     if (addrlen == 0) {
         fprintf(out, "  <empty, possibly corrupt>\n");
@@ -27,7 +29,7 @@ static inline void print_stacktrace(FILE *out = stderr, unsigned int max_frames
 
     // resolve addresses into strings containing "filename(function+address)",
     // this array must be free()-ed
-    char * *symbollist = backtrace_symbols(addrlist, addrlen);
+    char * *symbollist = backtrace_symbols(addrlist.data(), addrlen);
 
     // allocate string which will be filled with the demangled function name
     size_t funcnamesize = 256;