base: Add cmake wrapper scripts for CMAKE_TOOLCHAIN_FILE

All images should define this variables.

Disable build tests on the base image because it is not configured for cross
compiling.

imagefiles/ccmake.sh

@@ -0,0 +1,6 @@
+#!/bin/sh
+
+# Always pass the CMAKE_TOOLCHAIN_FILE variable to CMake when inside a
+# dockcross environment -- the CMAKE_TOOLCHAIN_FILE environmental variable is
+# always set in this context
+exec /usr/bin/ccmake -DCMAKE_TOOLCHAIN_FILE:FILEPATH=${CMAKE_TOOLCHAIN_FILE} "$@"

imagefiles/cmake.sh

@@ -0,0 +1,6 @@
+#!/bin/sh
+
+# Always pass the CMAKE_TOOLCHAIN_FILE variable to CMake when inside a
+# dockcross environment -- the CMAKE_TOOLCHAIN_FILE environmental variable is
+# always set in this context
+exec /usr/bin/cmake -DCMAKE_TOOLCHAIN_FILE:FILEPATH=${CMAKE_TOOLCHAIN_FILE} "$@"