Add custom assertion mechanism with backtrace printing

This change will allow getting more complete reports from assertion
failures. This will smooth the the bug report process, as users won't
have to get a backtrace from a debugger. As part of this change,
assertions are now enabled in release builds of the compiler, as
discussed in #1553. They still are disabled in release builds of the
runtime.

In the future, this system could be extended with even more precise
information like line numbers. Parsing the debug information of the
executables and libraries will be required for this.

Closes #1553.

Makefile

@@ -379,6 +379,8 @@ ifneq (,$(filter $(OSTYPE), osx freebsd))
 endif
 
 # target specific build options
+libponyrt.buildoptions = -DPONY_NO_ASSERT
+
 libponyc.buildoptions = -D__STDC_CONSTANT_MACROS
 libponyc.buildoptions += -D__STDC_FORMAT_MACROS
 libponyc.buildoptions += -D__STDC_LIMIT_MACROS
@@ -398,6 +400,8 @@ libgbenchmark.buildoptions := -DHAVE_POSIX_REGEX
 
 ponyc.buildoptions = $(libponyc.buildoptions)
 
+ponyc.linkoptions += -rdynamic
+
 ifeq ($(OSTYPE), linux)
   libponyrt-pic.buildoptions += -fpic
 endif

src/common/ponyassert.h

@@ -0,0 +1,21 @@
+#ifndef PLATFORM_PONYASSERT_H
+#define PLATFORM_PONYASSERT_H
+
+#include "platform.h"
+
+PONY_EXTERN_C_BEGIN
+
+#if defined(NDEBUG) && defined(PONY_NO_ASSERT)
+#  define pony_assert(expr) ((void)0)
+#else
+#  define pony_assert(expr) \
+    ((expr) ? (void)0 : \
+      ponyint_assert_fail(#expr, __FILE__, __LINE__, __func__))
+#endif
+
+void ponyint_assert_fail(const char* expr, const char* file, size_t line,
+  const char* func);
+
+PONY_EXTERN_C_END
+
+#endif