Put libcurl.a to DEP_CURL_ROOT/lib instead of DEP_CURL_ROOT/build

[mzygQAQ]

Currently, the libcurl.a was put into DEP_CURL_ROOT/build, which is not friendly for cmake's find_package.

[mzygQAQ]

DEP_CURL_ROOT/build
DEP_CURL_ROOT/include
DEP_CURL_ROOT/lib/pkgconfig

why dont put the static lib into lib