Remove obsolete seccomp_unwinder for legacy (pre-BPF) sandbox

Makefile.am

 ## Process this file with automake to produce Makefile.in
 
 # Copyright (c) 2011, Google Inc.
 # All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
@@ skipping 110 matching lines @@
 noinst_LIBRARIES += src/third_party/libdisasm/libdisasm.a
 endif
 
 if LINUX_HOST
 lib_LIBRARIES += src/client/linux/libbreakpad_client.a
 pkgconfig_DATA += breakpad-client.pc
 
 src_client_linux_libbreakpad_client_a_SOURCES = \
         src/client/linux/crash_generation/crash_generation_client.cc \
         src/client/linux/crash_generation/crash_generation_server.cc \
-        src/client/linux/dump_writer_common/seccomp_unwinder.cc \
         src/client/linux/dump_writer_common/thread_info.cc \
         src/client/linux/dump_writer_common/ucontext_reader.cc \
         src/client/linux/handler/exception_handler.cc \
         src/client/linux/handler/minidump_descriptor.cc \
         src/client/linux/log/log.cc \
         src/client/linux/microdump_writer/microdump_writer.cc \
         src/client/linux/minidump_writer/linux_dumper.cc \
         src/client/linux/minidump_writer/linux_ptrace_dumper.cc \
         src/client/linux/minidump_writer/minidump_writer.cc \
         src/client/minidump_file_writer.cc \
@@ skipping 308 matching lines @@
         -I$(top_srcdir)/src \
         -I$(top_srcdir)/src/testing/include \
         -I$(top_srcdir)/src/testing/gtest/include \
         -I$(top_srcdir)/src/testing/gtest \
         -I$(top_srcdir)/src/testing
 src_client_linux_linux_client_unittest_shlib_LDFLAGS = \
         -shared \
         -Wl,-h,linux_client_unittest_shlib
 src_client_linux_linux_client_unittest_shlib_LDADD = \
         src/client/linux/crash_generation/crash_generation_client.o \
-        src/client/linux/dump_writer_common/seccomp_unwinder.o \
         src/client/linux/dump_writer_common/thread_info.o \
         src/client/linux/dump_writer_common/ucontext_reader.o \
         src/client/linux/handler/exception_handler.o \
         src/client/linux/handler/minidump_descriptor.o \
         src/client/linux/log/log.o \
         src/client/linux/microdump_writer/microdump_writer.o \
         src/client/linux/minidump_writer/linux_dumper.o \
         src/client/linux/minidump_writer/linux_ptrace_dumper.o \
         src/client/linux/minidump_writer/minidump_writer.o \
         src/client/minidump_file_writer.o \
@@ skipping 885 matching lines @@
         src/tools/windows/converter/ms_symbol_server_converter.h \
         src/tools/windows/converter/ms_symbol_server_converter.vcproj \
         src/tools/windows/dump_syms/dump_syms.cc \
         src/tools/windows/dump_syms/dump_syms.vcproj \
         src/tools/windows/dump_syms/run_regtest.sh \
         src/tools/windows/dump_syms/testdata/dump_syms_regtest.cc \
         src/tools/windows/dump_syms/testdata/dump_syms_regtest.pdb \
         src/tools/windows/dump_syms/testdata/dump_syms_regtest.sym \
         src/tools/windows/symupload/symupload.cc \
         src/tools/windows/symupload/symupload.vcproj