Remove unused EXTERNAL_ variables from Makefile

They have been kept when the build system was refactored but it
turns out that they are not used at all (they are not passed on to
cmake).

JerryScript-DCO-1.0-Signed-off-by: Akos Kiss akiss@inf.u-szeged.hu

Author: akosthekiss

Makefile

@@ -94,16 +94,6 @@ export NATIVE_MODS := $(MCU_MODS) mem_stats mem_stress_test
 # External build configuration
  # Flag, indicating whether to use compiler's default libc (YES / NO)
   USE_COMPILER_DEFAULT_LIBC ?= NO
- # List of include paths for external libraries (semicolon-separated)
-  EXTERNAL_LIBS_INTERFACE ?=
- # External libc interface
-  ifeq ($(USE_COMPILER_DEFAULT_LIBC),YES)
-   ifneq ($(EXTERNAL_LIBC_INTERFACE),)
-    $(error EXTERNAL_LIBC_INTERFACE should not be specified in case compiler's default libc is used)
-   endif
-  endif
- # Compiler to use for external build
- EXTERNAL_C_COMPILER ?= arm-none-eabi-gcc
 
 # Directories
 export ROOT_DIR := $(shell pwd)