crt: Remove dummy __C_specific_handler implementation

mingw-w64 crt code does not use __C_specific_handler function since the
commit 271ce1baac1df4a062a419cd57120b4897c2fdfb ("crt: crt_handler: Switch
from __C_specific_handler+_gnu_exception_handler to __mingw_SEH_error_handler").

The current __C_specific_handler implementation is incomplete and therefore
it is not a good idea to pretend it is useful for applications.
So remove this incomplete / dummy implementation of __C_specific_handler.

Signed-off-by: LIU Hao <lh_mouse@126.com>

mingw-w64-crt/Makefile.am

diff --git a/mingw-w64-crt/Makefile.am b/mingw-w64-crt/Makefile.am
index a72bb51..8960f7a 100644
--- a/mingw-w64-crt/Makefile.am
+++ b/mingw-w64-crt/Makefile.am
@@ -507,7 +507,6 @@
 
 # Files included in libucrtapp.a
 src_ucrtapp=\
-  misc/__C_specific_handler.c \
   misc/longjmp.S \
   misc/setjmp.S \
   string/memchr.c \

mingw-w64-crt/misc/__C_specific_handler.c

diff --git a/mingw-w64-crt/misc/__C_specific_handler.c b/mingw-w64-crt/misc/__C_specific_handler.c
deleted file mode 100644
index 07f8927..0000000
--- a/mingw-w64-crt/misc/__C_specific_handler.c
+++ /dev/null
@@ -1,34 +0,0 @@
-/**
- * This file has no copyright assigned and is placed in the Public Domain.
- * This file is part of the mingw-w64 runtime package.
- * No warranty is given; refer to the file DISCLAIMER.PD within this package.
- */
-
-#include <excpt.h>
-
-#if defined(__x86_64__) || defined(__arm__) || defined(__aarch64__)
-EXCEPTION_DISPOSITION __cdecl
-__C_specific_handler(struct _EXCEPTION_RECORD *_ExceptionRecord,
-                     void *_EstablisherFrame,
-                     struct _CONTEXT *_ContextRecord,
-                     struct _DISPATCHER_CONTEXT *_DispatcherContext)
-{
-  (void)_ExceptionRecord;
-  (void)_EstablisherFrame;
-  (void)_ContextRecord;
-  (void)_DispatcherContext;
-  // TODO A more comprehensive implementation. Normally this is only used
-  // by the toplevel SEH handler for uncaught exceptions, for calling
-  // signal handlers. If signal handling isn't used, this no-op implementation
-  // should be ok. Wine does contain a supposedly correct implementation of
-  // this for x86_64 at least.
-  return ExceptionContinueSearch;
-}
-
-EXCEPTION_DISPOSITION
-(__cdecl *__MINGW_IMP_SYMBOL(__C_specific_handler))(
-    struct _EXCEPTION_RECORD *_ExceptionRecord,
-    void *_EstablisherFrame,
-    struct _CONTEXT *_ContextRecord,
-    struct _DISPATCHER_CONTEXT *_DispatcherContext) = __C_specific_handler;
-#endif