scrips/functions: fix downloads using curl

By default curl doesn't folow redirects. This breaks sourceforge downloads.
Add the -L option to curl to fix this.

Curl also downloads the html as a file even when it gets a 404. This breaks
http downloads when using the failback system. Add the -f option to curl to fix
this.

Signed-off-by: Richard Strand <richard.strand@icomera.com>

reporter_name="Yann E. MORIN"

reporter_url="http://ymorin.is-a-geek.org/projects/crosstool"

reporter_comment="Experimental toolchain for ARM cortex-m3 in Thumb-only, noMMU, and newlib."