Fixed Mono install in build script.
Fixed Mono install in build script.

u255436/CppSharp,mohtamohit/CppSharp,mono/CppSharp,genuinelucifer/CppSharp,genuinelucifer/CppSharp,ktopouzi/CppSharp,ktopouzi/CppSharp,mohtamohit/CppSharp,zillemarco/CppSharp,genuinelucifer/CppSharp,zillemarco/CppSharp,mohtamohit/CppSharp,inordertotest/CppSharp,zillemarco/CppSharp,genuinelucifer/CppSharp,zillemarco/CppSharp,genuinelucifer/CppSharp,mono/CppSharp,inordertotest/CppSharp,ddobrev/CppSharp,ktopouzi/CppSharp,ddobrev/CppSharp,u255436/CppSharp,mohtamohit/CppSharp,mono/CppSharp,mono/CppSharp,inordertotest/CppSharp,mono/CppSharp,inordertotest/CppSharp,zillemarco/CppSharp,u255436/CppSharp,inordertotest/CppSharp,ddobrev/CppSharp,ddobrev/CppSharp,ktopouzi/CppSharp,mohtamohit/CppSharp,u255436/CppSharp,ddobrev/CppSharp,ktopouzi/CppSharp,mono/CppSharp,u255436/CppSharp