Build: Added option to treat warnings as errors

Useful for CI.

Change-Id: I68b5acc949de69f1f7fb502bdc8efbbb659c3155
Signed-off-by: Bohdan Hunko <Bohdan.Hunko@infineon.com>
diff --git a/toolchain_ARMCLANG.cmake b/toolchain_ARMCLANG.cmake
index 581bcfd..7791982 100644
--- a/toolchain_ARMCLANG.cmake
+++ b/toolchain_ARMCLANG.cmake
@@ -115,6 +115,7 @@
     $<$<COMPILE_LANGUAGE:ASM>:-masm=armasm>
     $<$<AND:$<COMPILE_LANGUAGE:C>,$<BOOL:${TFM_DEBUG_SYMBOLS}>>:-g>
     $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<BOOL:${TFM_DEBUG_SYMBOLS}>>:-g>
+    $<$<AND:$<COMPILE_LANGUAGE:C,CXX>,$<BOOL:${CONFIG_TFM_WARNINGS_ARE_ERRORS}>>:-Werror>
 )
 
 add_link_options(