Summary: * Read armV7-A/R reference manual; crosstool-ng patches and wrapper scripts.

Details: 1. Patches for crosstool-ng: * Fix symlink issue when CT_USE_SYSROOT is not enabled. * Update sample/linaro-arm-none-eabi (baremetal) to disable SYSROOT. So that both include and lib files are in the same dir. 2. Study armV7-A/R reference manual. 3. Validate embedded toolchain Dec. release. 4. Enhance the wrapper to use crosstool-ng for embedded toolchain.

Plan: * Ramp-up on gcc.

Best regards! -Zhenqiang