dontmerge: add custom ARC u-boot for uimage support

eventually we should from open source, but it's not upstream yet
gdb: arc: Use git instead of website

Signed-off-by: Mischa Jonker <mjonker@synopsys.com>
binutils: arc: Use git instead of website

Signed-off-by: Mischa Jonker <mjonker@synopsys.com>
gcc: arc: Download from github instead of Synopsys website

The github release mechanism only supports .tar.gz, hence the ugly
GCC_UNPACK variable.

Signed-off-by: Mischa Jonker <mjonker@synopsys.com>
uclibc: arc: Use git instead of website

Signed-off-by: Mischa Jonker <mjonker@synopsys.com>
apply-patches: Don't return error code when patch directory doesn't exist

Some versions of packages may not need patches.

Signed-off-by: Mischa Jonker <mjonker@synopsys.com>