cpu/stm32f0: c++: initial support for c++, added _kill (weak) and weak attribute for _kill_r

boards/stm32f0discovery: provided c++ feature (cpp)

boards/stm32f0discovery/Makefile.features

@@ -1 +1 @@
-FEATURES_PROVIDED += periph_adc periph_gpio periph_spi periph_uart
+FEATURES_PROVIDED += periph_adc periph_gpio periph_spi periph_uart cpp

boards/stm32f0discovery/Makefile.include

@@ -17,6 +17,7 @@ export PORT
 # define tools used for building the project
 export PREFIX = arm-none-eabi-
 export CC = $(PREFIX)gcc
+export CXX = $(PREFIX)g++
 export AR = $(PREFIX)ar
 export AS = $(PREFIX)as
 export LINK = $(PREFIX)gcc
@@ -41,6 +42,10 @@ export FFLAGS = write bin/$(BOARD)/$(APPLICATION).hex 0x08000000
 export DEBUGGER_FLAGS = $(RIOTBOARD)/$(BOARD)/dist/gdb.conf bin/$(BOARD)/$(APPLICATION).elf
 export TERMFLAGS += -p "$(PORT)"
 
+# unwanted (CXXUWFLAGS) and extra (CXXEXFLAGS) flags for c++
+export CXXUWFLAGS +=
+export CXXEXFLAGS +=
+
 # use the nano-specs of the NewLib when available
 ifeq ($(shell $(LINK) -specs=nano.specs -E - 2>/dev/null >/dev/null </dev/null ; echo $$?),0)
 export LINKFLAGS += -specs=nano.specs -lc -lnosys

cpu/stm32f0/syscalls.c

@@ -156,6 +156,7 @@ int _getpid(void)
  *
  * @return      TODO
  */
+__attribute__ ((weak))
 int _kill_r(struct _reent *r, int pid, int sig)
 {
     r->_errno = ESRCH;                      /* not implemented yet */
@@ -324,3 +325,18 @@ int _unlink_r(struct _reent *r, char* path)
     r->_errno = ENODEV;                     /* not implemented yet */
     return -1;
 }
+
+/**
+ * @brief Send a signal to a thread
+ *
+ * @param[in] pid the pid to send to
+ * @param[in] sig the signal to send
+ *
+ * @return TODO
+ */
+__attribute__ ((weak))
+int _kill(int pid, int sig)
+{
+    errno = ESRCH;                         /* not implemented yet */
+    return -1;
+}