since configure supports only native configuration
a file 'cross-tcc.mak' needs to be created manually.
It is included in the Makefile if present.

# ----------------------------------------------------
# Example config-cross.mak:
#
# windows -> i386-linux cross-compiler
# (it expects the linux files in <prefix>/i386-linux)

ROOT-i386 = {B}/i386-linux
CRT-i386 = $(ROOT-i386)/usr/lib
LIB-i386 = $(ROOT-i386)/lib:$(ROOT-i386)/usr/lib
INC-i386 = {B}/lib/include:$(ROOT-i386)/usr/include
DEF-i386 += -D__linux__

# ----------------------------------------------------

Also:
- use libtcc1-<target>.a instead of directories
- add dummy arm assembler
- remove include dependencies from armeabi.c/lib-arm64.c
- tccelf/ld_add_file: add SYSROOT (when defined) to absolute
  filenames coming from ld-scripts

- tccgen.c/tcc.h: allow function declaration after use:
      int f() { return g(); }
      int g() { return 1; }
  may be a warning but not an error
  see also 76cb1144ef91924c53c57ea71e6f67ce73ce1cc6

- tccgen.c: redundant code related to inline functions removed
  (functions used anywhere have sym->c set automatically)

- tccgen.c: make 32bit llop non-equal test portable
  (probably not on C67)

- dynarray_add: change prototype to possibly avoid aliasing
  problems or at least warnings

- lib/alloca*.S: ".section .note.GNU-stack,"",%progbits" removed
  (has no effect)

- tccpe: set SizeOfCode field (for correct upx decompression)

- libtcc.c: fixed alternative -run invocation
      tcc "-run -lxxx ..." file.c
  (meant to load the library after file).
  Also supported now:
      tcc files ... options ... -run @ arguments ...

This provides a simple implementation of alloca for ARM (and enables
the associated testcase).  As tcc for ARM doesn't contain an assembler,
we'll have to resort using gcc for compiling it.