cpu/msp430_common: Fix linking with binutils 2.40

An `INSERT AFTER` directive no longer can refer to a different linker
script included with `-T path/to/script.ld`. Instead, this adds wrapper
linker scripts that just `INCLUDE` the three individual linker scripts.
This way, the xfa.ld can safely refer back to sections defined in
the vendor linker script.

cpu/msp430_common/ldscripts/riot-msp430f1611.ld

@@ -0,0 +1,3 @@
+INCLUDE msp430f1611.ld
+INCLUDE msp430_common.ld
+INCLUDE xfa.ld

cpu/msp430_common/ldscripts/riot-msp430f1612.ld

@@ -0,0 +1,3 @@
+INCLUDE msp430f1612.ld
+INCLUDE msp430_common.ld
+INCLUDE xfa.ld

cpu/msp430_common/ldscripts/riot-msp430f1617.ld

@@ -0,0 +1,3 @@
+INCLUDE msp430f1617.ld
+INCLUDE msp430_common.ld
+INCLUDE xfa.ld

makefiles/arch/msp430.inc.mk

@@ -14,10 +14,10 @@ CFLAGS += $(CFLAGS_CPU) $(CFLAGS_LINK) $(CFLAGS_DBG) $(CFLAGS_OPT)
 ASFLAGS += $(CFLAGS_CPU) --defsym $(CPU_MODEL)=1 $(CFLAGS_DBG)
 
 LINKFLAGS += $(CFLAGS_CPU) $(CFLAGS_DBG) $(CFLAGS_OPT)
-LINKFLAGS += -Wl,--gc-sections -Wl,-L$(MSP430_SUPPORT_FILES)/include
-LINKFLAGS += -T $(MSP430_SUPPORT_FILES)/include/$(CPU_MODEL).ld
-LINKFLAGS += -T $(RIOTCPU)/msp430_common/ldscripts/msp430_common.ld
-LINKFLAGS += $(RIOTCPU)/msp430_common/ldscripts/xfa.ld
+LINKFLAGS += -Wl,--gc-sections
+LINKFLAGS += -Wl,-L$(MSP430_SUPPORT_FILES)/include
+LINKFLAGS += -Wl,-L$(RIOTCPU)/msp430_common/ldscripts
+LINKFLAGS += -T riot-$(CPU_MODEL).ld
 
 OPTIONAL_CFLAGS_BLACKLIST += -fdiagnostics-color
 OPTIONAL_CFLAGS_BLACKLIST += -Wformat-overflow