northteam

fix MbedTLS building failure with clang on macOS

2

*Issue #, if available:* *Description of changes:* When building MbedTLS with clang on macOS, an 'unused-but-set-parameter' error will be emitted on 'library/psa_crypto.c'. > [ 28%] Building C object library/CMakeFiles/mbedcrypto_static.dir/poly1305.c.o >...

``` val xml = abc val text = (xml\"text").text ``` `\` was treated as escape character instead of xpath child searching function. Current solution: add a space after `\`.