meta: toolchain-shar-relocate.sh: Do not use $target_sdk_dir as regex

The $target_sdk_dir path might contain special characters, for example if
the path is /opt/poky/3.2+snapshot . Prevent grep from interpreting those
as part of the regex by using the -F parameter and multiple -e parameters
to specify which strings to filter out. Also note that the previous regex
was using asterisk as wildcard (e.g. environment-setup-*), but that should
have been regex (e.g. environment-setup-.*, with dot) to match correctly,
this is also fixed by this change.

Fixes: 97213786 ("toolchain-shar-template.sh: Make relocation optional.")
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Joshua Watt <JPEWhacker@gmail.com>
Cc: Krzysztof Zawadzki <krzysztof.zawadzki@nokia.com>
Cc: Randy Witt <randy.e.witt@linux.intel.com>
Cc: Richard Purdie <richard.purdie@linuxfoundation.org>
Cc: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>