compile.sh: local.properties init: fix regex matching android sdk/ndk variables.

grep was interpreting the variables as regexes intended to
match themselves. this could cause errors or false positives/negatives if the
variables contain regex metacharacters. now the variables are escaped to
produce regexes that will always and only match themselves.

Signed-off-by: Geoffrey Métais <geoffrey.metais@gmail.com>