explicitly specify TOOLCHAIN

Swift can only build with the gcc toolchain; if the default toolchain is clang,
we need to reset the toolchain to gcc. (Note that Swift itself uses its own
clang.)

Author: lhoward

classes/swift-cmake-base.bbclass

@@ -1,6 +1,7 @@
 inherit cmake
 
-DEPENDS_append += " swift-native libgcc gcc glibc "
+# avoid conflicts with meta-clang
+TOOLCHAIN = "gcc"
 
 DEPENDS:append = " swift-native libgcc gcc glibc "
 

classes/swift.bbclass

@@ -1,3 +1,5 @@
+# avoid conflicts with meta-clang
+TOOLCHAIN = "gcc"
 
 DEPENDS += "swift-native glibc gcc libgcc swift-stdlib libdispatch libfoundation"