[=] fix search paths for ssl and crypto static libraries

[onehouwong]

When building xquic with BoringSSL by following the QuickStart Guide, the cmake script fails to locate the static libraries of the boringssl and crypto static libraries. See the error log below:

~/xquic/build$ cmake -DGCOV=on -DCMAKE_BUILD_TYPE=Debug -DXQC_ENABLE_TESTING=1 -DXQC_SUPPORT_SENDMMSG_BUILD=1 -DXQC_ENABLE_EVENT_LOG=1 -DXQC_ENABLE_BBR2=1 -DXQC_ENABLE_RENO=1 -DSSL_TYPE=${SSL_TYPE_STR} -DSSL_PATH=${SSL_PATH_STR} ..
-- The C compiler identification is GNU 9.5.0
-- The CXX compiler identification is GNU 9.5.0
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /usr/bin/cc - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/c++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Could NOT find SSL (missing: SSL_LIBRARY_STATIC CRYPTO_LIBRARY_STATIC)
CMake Error at CMakeLists.txt:69 (message):
  ssl module not found


-- Configuring incomplete, errors occurred!

This patch is to fix the search paths in cmake/FindSSL.cmake so that it can find the corresponding modules.

[CLAassistant]

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[Sy0307]

Hi, after tests we decide to merge it. Please pull the latest changes for us to merge this PR. Thanks.

[onehouwong]

Hi @Sy0307, I've pulled the latest changes

[Yanmei-Liu]

Looks good.