CMake: Add support for LPC176X targets

All LPC176X targets supported by Mbed OS
can now be built with CMake.

targets/TARGET_NXP/TARGET_LPC176X/CMakeLists.txt

@@ -0,0 +1,55 @@
+# Copyright (c) 2020 ARM Limited. All rights reserved.
+# SPDX-License-Identifier: Apache-2.0
+
+if("ARCH_PRO" IN_LIST MBED_TARGET_LABELS)
+    target_include_directories(mbed-core
+        INTERFACE
+            TARGET_ARCH_PRO
+    )
+elseif("MBED_LPC1768" IN_LIST MBED_TARGET_LABELS)
+    target_include_directories(mbed-core
+        INTERFACE
+            TARGET_MBED_LPC1768
+    )
+endif()
+
+if(${MBED_TOOLCHAIN} STREQUAL "ARM")
+    set(STARTUP_FILE device/TOOLCHAIN_ARM_STD/startup_LPC17xx.S)
+    set(LINKER_FILE device/TOOLCHAIN_ARM_STD/LPC1768.sct)
+elseif(${MBED_TOOLCHAIN} STREQUAL "GCC_ARM")
+    set(STARTUP_FILE device/TOOLCHAIN_GCC_ARM/startup_LPC17xx.S)
+    set(LINKER_FILE device/TOOLCHAIN_GCC_ARM/LPC1768.ld)
+endif()
+
+set_property(GLOBAL PROPERTY MBED_TARGET_LINKER_FILE ${CMAKE_CURRENT_SOURCE_DIR}/${LINKER_FILE})
+
+target_include_directories(mbed-core
+    INTERFACE
+        .
+        device
+)
+
+target_sources(mbed-core
+    INTERFACE
+        analogin_api.c
+        analogout_api.c
+        can_api.c
+        gpio_api.c
+        gpio_irq_api.c
+        i2c_api.c
+        pinmap.c
+        port_api.c
+        pwmout_api.c
+        reset_reason.c
+        rtc_api.c
+        serial_api.c
+        sleep.c
+        spi_api.c
+        us_ticker.c
+        watchdog_api.c
+
+        device/CRP.c
+        device/flash_api.c
+        device/system_LPC17xx.c
+        ${STARTUP_FILE}
+)