jerry.cmake: Disable LTO for JerryScript build

With LTO compiling enabled, and Zephyr SDk 0.10.0, during final Zephyr
link (which isn't done with LTO option), for armv7m targets, weird
errors are thrown:

zephyr-sdk-0.10.0/arm-zephyr-eabi/.../arm-zephyr-eabi/bin/ld: error:
zephyr_prebuilt.elf uses VFP register arguments, /tmp/ccTrD4ap.ltrans1.ltrans.o does not

Note that both JerryScript and Zephyr seem to be built with correct and
consistent target options, which enable VFP usage.

Disabling LTO option for JerryScript build fixes this issue.

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>

cmake/jerry.cmake

@@ -45,7 +45,7 @@ set(CMAKE_ARGS
   -DCMAKE_C_COMPILER_WORKS=TRUE
   -DCMAKE_SYSTEM_NAME=Zephyr
   -DENABLE_ALL_IN_ONE=OFF
-  -DENABLE_LTO=ON
+  -DENABLE_LTO=OFF
   -DEXTERNAL_COMPILE_FLAGS=${external_project_cflags}
   -DFEATURE_ERROR_MESSAGES=ON
   -DFEATURE_DEBUGGER=${DEBUGGER}