make the hello example work

Cargo.toml

@@ -12,13 +12,16 @@ version = "0.2.7"
 # cortex-m = "0.4.0"
 # cortex-m-rt = "0.4.0"
 cortex-m-rt = { git = "https://github.com/japaric/cortex-m-rt", branch = "stable" }
-# cortex-m-semihosting = "0.2.0"
 # panic-loop = { path = "../panic-loop" }
 panic-abort = "0.1.1"
 # panic-semihosting = "0.1.0"
 # Uncomment for the allocator example.
 #alloc-cortex-m = "0.3.3"
 
+[dependencies.cortex-m-semihosting]
+default-features = false
+version = "0.2.1"
+
 # Uncomment for the device example.
 # [dependencies.stm32f103xx]
 # features = ["rt"]