[GDB] Fix compiling error when not enable GDB.
[LIBC] Use RT_USING_LIBC instead of libs option for each compiler
[BSP] use RT_USING_LIBC instead of RT_USING_NEWLIB
Merge pull request #360 from BernardXiong/master

[LIBC] Use RT_USING_LIBC instead of libs option for each compiler
[LIBC] fix the fopen/open issue in armlibc
[C++] Add cplusplus component
[Drivers] Add sensor framework
Merge remote-tracking branch 'upstream/master'
[BSP] use RT_USING_LIBC instead of RT_USING_NEWLIB
[BSP] Update C++ compiling options
[BSP] Fix the gcc compiling issue in LPC408x bsp
[NFS] fix opendir failed issue.
[BSP] fix GCC compiling issue when enable C++ support
[C++] fix the ctors initialization issue
Merge pull request #361 from BernardXiong/master

Add cplusplus and sensor framework.
Merge branch 'master' of https://github.com/BernardXiong/rt-thread
Merge remote-tracking branch 'upstream/master'
Merge pull request #362 from BernardXiong/master

[C++] fix GCC compiling issue.
[Sensor] code cleanup
Merge pull request #363 from BernardXiong/master

[Sensor] code cleanup