V8_Fatal now prints C++ stack trace in debug mode.

build/common.gypi

Index: build/common.gypi
diff --git a/build/common.gypi b/build/common.gypi
index e68ee15fdeeed5fd33759dc40f46c9f6e1862d03..7e7b1b417da5343faff0d652b13673e8aadec528 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -68,6 +68,8 @@
 
     'v8_enable_debugger_support%': 1,
 
+    'v8_enable_backtrace%': 0,
+
     'v8_enable_disassembler%': 0,
 
     'v8_enable_gdbjit%': 0,
@@ -368,6 +370,10 @@
             'cflags': [ '-Wall', '<(werror)', '-W', '-Wno-unused-parameter',
                         '-Wnon-virtual-dtor', '-Woverloaded-virtual' ],
           }],
+          ['OS=="linux" and v8_enable_backtrace==1', {
+            # Support for backtrace_symbols.
+            'ldflags': [ '-rdynamic' ],
+          }],
           ['OS=="android"', {
             'variables': {
               'android_full_debug%': 1,