[Native] Drop explicit -fPIC flag setup

We don't need to explicitly set -fPIC flag everywhere
because since d82109cc92
it is set by default for all ClangArgs users.

kotlin-native/libclangext/build.gradle.kts

@@ -31,9 +31,6 @@ native {
                           "-Isrc/main/include",
                           "-I${project.findProperty("llvmDir")}/include",
                           "-DLLVM_DISABLE_ABI_BREAKING_CHECKS_ENFORCING=1")
-    if (!org.jetbrains.kotlin.konan.target.HostManager.hostIsMingw) {
-        cxxflags += "-fPIC"
-    }
     if (libclangextEnabled) {
         cxxflags += "-DLIBCLANGEXT_ENABLE=1"
     }