build: Move common DS_xxxx variables in Maketype file.

There is no point in setting these variables for every Maketype
invocation since they are the same in most of the cases.

This patch allows the following variables to be overriden when
running `make`: DS_CC, DS_AR, DS_LD, DS_RL, DS_ST, DS_ARFLAGS and
DS_CFLAGS
build: Remove DS_AWK variable since it is not used anywhere.
build: Replace "unkown" with "unknown" in cross-arm{BE,LE}-... targets.

This fixes typos in two targets - cross-armBE-unkown-linux, cross-armLE-unkown-linux

If somebody depends on the wrong spelling he should update his build
scripts to the new names - cross-armBE-unknown-linux, cross-armLE-unknown-linux
build: Add 'unkown' aliases for cross-arm{BE,LE}-... targets.

The original misspelled targets are working now.
build: Introduce CROSS variable and use it to clean build tools setup.

When cross compiling in most of the cases the tool names are different only
by the cross compilation prefix added in front of the tool names. This patch
introduces CROSS variable to allows setting this prefix.

With this it is enough to run `make CROSS=/path/to/toolchain/sh4-linux- target`
or if tools are in the PATH `make CROSS=sh4-linux- target` and all tools will
be set. You can change both CROSS and DS_XX variables for example:
`make CROSS=/path/to/toolchain/osx-linux- DS_CC=clang target`
build: OS_CULI variable is not used anywhere, remove it.
build: Introduce LIB_PTHREAD variable.

Add LIB_PTHREAD variable in Maketype to cleanup OS_PTLI and DS_OPTS
variables. To override it use `make LIB_PTHREAD=xxxxxxxx`
build: Merge OS_PTLI with OS_LIBS.

OS_PTLI is used only in two places and they can be merged with OS_LIBS.
build: Introduce LIB_MATH and cleanup OS_LIBS.
build: Rename LIBSSL to LIB_SSL to match other LIB_xxx variables.
build: Rename KFLAG to DEFINES.

Now you can add any define to the build by running:
  `make DEFINES="-Dblah -Dblah2 ..."`
build: Add LIB_CRYPTO and NO_LIBCRYPTO variables.

This cleans up OS_LIBS by moving libcrypto to Maketype. The targets
that do not need libcrypto should set NO_LIBCRYPTO=1 variable.
build: Move definitions of CS_SVN_VERSION and CS_CONFDIR to Maketype.

This cleans up all of DS_OPTS and allows CONF_DIR to be set as variable
when building. For example to change conf directory you can use:
  `make CONF_DIR=/etc/oscam target`
build: Set compiler optimizations and warning settings in Maketype.

Now you can set CC_FLAGS, CC_FLAGS_DEBUG and CC_FLAGS_WARN variables
to control what flags will the compiler use. Use `make DEBUG=1` to
get debug build.
build: Do not set HAVE_DVBAPI for i386-pc-linux-debug build.

This flag should come from the config.
build: Do not set unknown variable in alpha-dec-osf5.1 target.
build: Add support for setting USE_LIBUSB, LIBUSB and LIBUSB_DEFS.

These three variables control the compilation with libusb.
build: Add support for setting USE_PCSC, PCSC and PCSC_DEFS.

This three variables control the compilation with PCSC.
build: Allow build type to be set by TYPE variable.

For example now you may use `make TYPE=sh4-linux CROSS=sh4-linux- DEFINES="-DOS_LINUX -DSH4"`
to build OSCAM with sh4 cross compilers.
build: Move targets into separate files under toolchains/ directory.

This would allow easier adding of new targets without the need
to patch Makefile. All files matching toolchains/target_*.make
are automatically included by the Makefile.