examples: cleanup examples directory

Following changes are done as a part of cleanup:

1. Moved the platform specific `C` examples from top level examples/
directory to platform/ subdirectory and renamed helloedison.c to
gpio_edison.c

2. C specific examples are moved to a new c/ subdirectory. As a part
of this process, examples are modified to follow same standards
and few new examples are also added.

3. Include the newly added C examples to relevant API documentation

4. Ran clang-format for all source files in c/, c++/, platform/
subdirectories

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Brendan Le Foll <brendan.le.foll@intel.com>

examples/c/CMakeLists.txt

@@ -0,0 +1,36 @@
+add_executable(aio aio.c)
+add_executable(gpio gpio.c)
+add_executable(gpio_advanced gpio_advanced.c)
+add_executable(hellomraa hellomraa.c)
+add_executable(i2c_hmc5883l i2c_hmc5883l.c)
+add_executable(i2c_mpu6050 i2c_mpu6050.c)
+add_executable(led led.c)
+add_executable(pwm pwm.c)
+add_executable(spi spi.c)
+add_executable(uart uart.c)
+add_executable(uart_advanced uart_advanced.c)
+if (NOT ANDROID_TOOLCHAIN)
+  add_executable(iio iio.c)
+endif()
+
+include_directories(${PROJECT_SOURCE_DIR}/api)
+include_directories(${PROJECT_SOURCE_DIR}/api/mraa)
+
+target_link_libraries(aio mraa)
+target_link_libraries(gpio mraa)
+target_link_libraries(gpio_advanced mraa)
+target_link_libraries(hellomraa mraa)
+target_link_libraries(i2c_hmc5883l mraa m)
+target_link_libraries(i2c_mpu6050 mraa)
+target_link_libraries(led mraa)
+target_link_libraries(pwm mraa)
+target_link_libraries(spi mraa)
+target_link_libraries(uart mraa)
+target_link_libraries(uart_advanced mraa)
+if (NOT ANDROID_TOOLCHAIN)
+  target_link_libraries(iio mraa)
+endif()
+if (ONEWIRE)
+  add_executable (uart_ow uart_ow.c)
+  target_link_libraries (uart_ow mraa)
+endif ()