Fix typo buiding -> building

Signed-off-by: Thomas De Schampheleire <thomas.de.schampheleire@gmail.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

toolchain/toolchain-common.in

@@ -105,4 +105,4 @@ config BR2_TARGET_OPTIMIZATION
 config BR2_TARGET_LDFLAGS
 	string "Target linker options"
 	help
-	  Extra options to pass to the linker when buiding for the target.
+	  Extra options to pass to the linker when building for the target.