add cmake configuration attr (#1339)

`cmake()` appends a `--config` arg to every `cmake --install` and `cmake
--build`.

The default value of this arg is derived from the COMPILATION_MODE env
var.

This PR allows `cmake()` to override this value.

Author: matt-sm

foreign_cc/cmake.bzl

@@ -206,7 +206,8 @@ def _create_configure_script(configureParameters):
 
     cmake_commands = []
 
-    configuration = "Debug" if is_debug_mode(ctx) else "Release"
+    default_configuration = "Debug" if is_debug_mode(ctx) else "Release"
+    configuration = default_configuration if not ctx.attr.configuration else ctx.attr.configuration
 
     data = ctx.attr.data + ctx.attr.build_data
 
@@ -365,6 +366,15 @@ def _attrs():
             mandatory = False,
             default = {},
         ),
+        "configuration": attr.string(
+            doc = (
+                "Override the `cmake --build` and `cmake --install` `--config` configuration. " +
+                "If left empty, the value of this arg will be determined by the COMPILATION_MODE env var: " +
+                "dbg will set `--config Debug` and all other modes will set --config Release."
+            ),
+            mandatory = False,
+            default = "",
+        ),
         "generate_args": attr.string_list(
             doc = (
                 "Arguments for CMake's generate command. Arguments should be passed as key/value pairs. eg: " +