tcc: re-enable correct option -r support

Forgot about it.  It allows to compile several
sources (and other .o's) to one single .o file;

    tcc -r -o all.o f1.c f2.c f3.S o4.o ...

Also:
- option -fold-struct-init-code removed, no effect anymore
- (tcc_)set_environment() moved to tcc.c
- win32/lib/(win)crt1 minor fix & add dependency
- debug line output for asm (tcc -c -g xxx.S) enabled
- configure/Makefiles: x86-64 -> x86_64 changes
- README: cleanup

Changelog

@@ -16,14 +16,14 @@ Platforms:
 - vastly improved support for ARM hard float calling convention
    (Thomas Preud'homme, Daniel Glöckner)
 - provide a runtime library for ARM (Thomas Preud'homme)
-- many x86-64 ABI fixes incl. XMM register passing and tests (James Lyon)
+- many x86_64 ABI fixes incl. XMM register passing and tests (James Lyon)
 - ABI tests with native compiler using libtcc (James Lyon)
 - UNICODE startup code supports wmain and wWinMain (YX Hao)
 
 Features:
 - VLA (variable length array) improved (James Lyon, Pip Cet)
 - import functions by ordinal in .def files on windows (YX Hao)
-- x86/x86-64 assembler much improved (Michael Matz)
+- x86/x86_64 assembler much improved (Michael Matz)
 - simple dead code suppression (Edmund Grimley Evans, Michael Matz, grischka)
 - implement round/fmin/fmax etc. math on windows (Avi Halachmi)
 - #pragma once support (Sergey Korshunoff, Vlad Vissoultchev, ...)