NetSurf Build System / Atari support

Hello,

It looks like the current netsurf buildsystem isn't able to compile
correct executables for the atari target, this is especially bad when
running
on coldfire, where the build failure results in illegal instructions
(when m68k CPU emulation is turned off).
(the sdk build maybe suffers the same problem, but that's another
story)

On my local box I use Verbose mode of make, to see the actual compiler
commands.

Let's have a look at the atari support within the netsurf buildsystem:

--- snip ---

# FreeMiNT / atari
ifeq ($(TARGET),atari)
ifeq ($(HOST),atari)
# Building on FreeMiNT
# Nothing to do, as we assume the default tooling works
else
# Cross compiling for FreeMiNT

ATARIARCH ?= 68020-60

GCCSDK_INSTALL_ENV ?= /opt/netsurf/m68k-atari-mint
GCCSDK_INSTALL_CROSSBIN ?= /opt/netsurf/m68k-atari-mint/cross/bin
CC__ := $(GCCSDK_INSTALL_CROSSBIN)/m68k-atari-mint-gcc
CXX__ := $(GCCSDK_INSTALL_CROSSBIN)/m68k-atari-mint-g++
AR__ := $(GCCSDK_INSTALL_CROSSBIN)/m68k-atari-mint-ar

ifeq ($(ATARIARCH),68000)
ARCHFLAGS :=
ARCHDIR :=
endif
ifeq ($(ATARIARCH),68020-60)
ARCHFLAGS := -m$(ATARIARCH)
ARCHDIR := /$(ATARIARCH)
endif
ifeq ($(ATARIARCH),v4e)
ARCHFLAGS := -mcpu=5475
ARCHDIR := /m5475
endif

CFLAGS := $(CFLAGS) -U__STRICT_ANSI__
-I$(GCCSDK_INSTALL_ENV)/include $(ARCHFLAGS)
CXXFLAGS := $(CXXFLAGS) -U__STRICT_ANSI__
-I$(GCCSDK_INSTALL_ENV)/include $(ARCHFLAGS)
LDFLAGS := $(LDFLAGS) -L$(GCCSDK_INSTALL_ENV)/lib$(ARCHDIR)

PREFIX ?= $(GCCSDK_INSTALL_ENV)
endif
endif

--- snip ---

First thing to notice is the fact that it assumes you do pass the
environment variable ATARIARCH
to specify the CPU type. If you do not specify this variable, the cpu
defaults to 68020-60, which
is definitly wrong for coldfire compilation.

I'm assuming that the netsurf build system does not set ATARIARCH.
I'm open for suggestions, how to specify and resolve the CPU type
differently, of course.

Also look at the output of libcss build:
http://ci.netsurf-browser.org/jenkins/job/libcss/TARGET=m5475-atari-mint,label=other/86/consoleText

You can not see which compiler was used. You can not see which
CFLAGS/LDFLAGS where used.

Second thing to notice is the fact that it assumes the m68k-atari-mint
toolchain to be used:
CC__ := $(GCCSDK_INSTALL_CROSSBIN)/m68k-atari-mint-gcc
CXX__ := $(GCCSDK_INSTALL_CROSSBIN)/m68k-atari-mint-g++
AR__ := $(GCCSDK_INSTALL_CROSSBIN)/m68k-atari-mint-ar

When compiling for coldfire (the way it was meant to be: by setting
ATARIARCH) it will fail to find the compiler
because the m68k-atari-mint compiler is not located in the coldfire sdk
dirs.

Of course the script could be adjusted like this:
ifeq ($(ATARIARCH),v4e)
ARCHFLAGS := -mcpu=5475
ARCHDIR := /m5475
CC__ := $(GCCSDK_INSTALL_CROSSBIN)/m5475-atari-mint-gcc
CXX__ := $(GCCSDK_INSTALL_CROSSBIN)/m5475-atari-mint-g++
AR__ := $(GCCSDK_INSTALL_CROSSBIN)/m5475-atari-mint-ar
endif

But that would mean, that the average buildsystem user is not able to
compile netsurf
on his own box, when he doesn't want to use the m5475-atari-mint-xxx
provided by the netsurf sdk build.

As an example, just take this simple make command and see how it fails:

/media/src/netsurf.git/libnsgif$
GCCSDK_INSTALL_CROSSBIN=/opt/netsurf/m5475-atari-mint/cross/bin
GCCSDK_INSTALL_ENV=/opt/netsurf/m5475-atari-mint make TARGET=atari
ATARIARCH=v4e
/bin/sh: /opt/netsurf/m5475-atari-mint/cross/bin/m68k-atari-mint-gcc:
not found
/bin/sh: /opt/netsurf/m5475-atari-mint/cross/bin/m68k-atari-mint-gcc:
not found
/opt/netsurf/m5475-atari-mint/share/netsurf-buildsystem/makefiles/Makefile.tools:466:
*** Unable to detect toolchain. Schluss.

Using m68k-atari-mint-gcc to compile atari coldfire software is de
facto standard and
I don't want to explain people that things are different with netsurf
;)
However, if this is the only way to implement clean coldfire support in
the netsurf
buildsystem, I'm happy to take that pill.

Can we add the ATARIARCH environment variable, like it is done for the
netsurf build?
Valid values:

ATARIARCH=68020-60
ATARIARCH=v4e

The coldfire build will be broken then (look at the example above),
because it won't be able to find the toolchain (except it is explicitly
set), however, when that happens, I probably already fixed the toolchain
names for coldfire within the makefile.