Enable compiler specification via env. var. CC/CXX

Many build systems allow C and C++ compilers to be specified
via environment variables C and CXX.

This commit enables this for kaleidoscope-builder.

Furtheron, on unixoid systems virtual builds are possible through a
command line similar to

CXX=<path to C++ compiler> C=<path to C compiler> ARCH=virtual make

Signed-off-by: Florian Fleissner <florian.fleissner@inpartik.de>

bin/kaleidoscope-builder

@@ -62,12 +62,12 @@ enable_ccache () {
          mkdir -p "$CCACHE_WRAPPER_PATH"
       fi
       
-      if ! [ -h "${CCACHE_WRAPPER_PATH}/${COMPILER_PREFIX}gcc" ]; then
-         ln -s "$(command -v ccache)" "${CCACHE_WRAPPER_PATH}/${COMPILER_PREFIX}gcc"
+      if ! [ -h "${CCACHE_WRAPPER_PATH}/${COMPILER_PREFIX}${C_COMPILER_BASENAME}" ]; then
+         ln -s "$(command -v ccache)" "${CCACHE_WRAPPER_PATH}/${COMPILER_PREFIX}${C_COMPILER_BASENAME}"
       fi
       
-      if ! [ -h "${CCACHE_WRAPPER_PATH}/${COMPILER_PREFIX}g++" ]; then
-         ln -s "$(command -v ccache)" "${CCACHE_WRAPPER_PATH}/${COMPILER_PREFIX}g++"
+      if ! [ -h "${CCACHE_WRAPPER_PATH}/${COMPILER_PREFIX}${CXX_COMPILER_BASENAME}" ]; then
+         ln -s "$(command -v ccache)" "${CCACHE_WRAPPER_PATH}/${COMPILER_PREFIX}${CXX_COMPILER_BASENAME}"
       fi
       
       if ! [ -h "${CCACHE_WRAPPER_PATH}/${COMPILER_PREFIX}nm" ]; then
@@ -305,6 +305,8 @@ compile () {
 	      -built-in-libraries "${ARDUINO_PATH}/libraries" \
 	      -prefs "compiler.cpp.extra_flags=-std=c++11 -Woverloaded-virtual -Wno-unused-parameter -Wno-unused-variable -Wno-ignored-qualifiers ${ARDUINO_CFLAGS} ${LOCAL_CFLAGS}" \
 	      -prefs compiler.path=${COMPILER_PATH} \
+	      -prefs "compiler.c.cmd=${COMPILER_PREFIX}${C_COMPILER_BASENAME}" \
+	      -prefs "compiler.cpp.cmd=${COMPILER_PREFIX}${CXX_COMPILER_BASENAME}" \
 	      $CCACHE_ENABLE \
 	      -warnings all \
         ${ARDUINO_VERBOSE} \

etc/kaleidoscope-builder.conf

@@ -234,6 +234,9 @@ ARDUINO_IDE_VERSION="10607"
 # Allow the compiler path to be empty for virtual builds
 COMPILER_PATH="${COMPILER_PATH-${ARDUINO_TOOLS_PATH}/avr/bin/}"
 
+C_COMPILER_BASENAME=$(basename ${CC:-gcc})
+CXX_COMPILER_BASENAME=$(basename ${CXX:-g++})
+
 # Allow the compiler prefix to be empty for virtual builds
 COMPILER_PREFIX="${COMPILER_PREFIX-avr-}"
 AVR_SIZE="${AVR_SIZE:-${COMPILER_PATH}/${COMPILER_PREFIX}size}"
@@ -242,8 +245,8 @@ AVR_OBJDUMP="${AVR_OBJDUMP:-${COMPILER_PATH}/${COMPILER_PREFIX}objdump}"
 AVR_OBJCOPY="${AVR_OBJCOPY:-${COMPILER_PATH}/${COMPILER_PREFIX}objcopy}"
 AVR_NM="${AVR_NM:-${COMPILER_PATH}/${COMPILER_PREFIX}nm}"
 AVR_AR="${AVR_AR:-${COMPILER_PATH}/${COMPILER_PREFIX}ar}"
-AVR_GCC="${AVR_GCC:-${COMPILER_PATH}/${COMPILER_PREFIX}gcc}"
-AVR_GPLUSPLUS="${AVR_GCC:-${COMPILER_PATH}/${COMPILER_PREFIX}g++}"
+AVR_GCC="${AVR_GCC:-${COMPILER_PATH}/${COMPILER_PREFIX}${C_COMPILER_BASENAME}}"
+AVR_GPLUSPLUS="${AVR_GCC:-${COMPILER_PATH}/${COMPILER_PREFIX}${CXX_COMPILER_BASENAME}}"