Pass linker flags to the linker only once
Pass linker flags to the linker only once

Before, `make_gcc_arm` would export a makefile with both linker flags in
the `$(LD)` make variable and the `$(LD_FLAGS)` make variable. This only
affected GCC based makefiles, as the `$(LD)` make variable would only
contain the linker for both ARMC5 and IAR. This patch enforces the
`$(LD)` behavior of ARMC5 and IAR on all of the compilers by truncating
`$(LD)` to just the command

kl-cruz/mbed-os,karsev/mbed-os,mikaleppanen/mbed-os,screamerbg/mbed,nvlsianpu/mbed,nvlsianpu/mbed,monkiineko/mbed-os,andcor02/mbed-os,kjbracey-arm/mbed,bcostm/mbed-os,infinnovation/mbed-os,adustm/mbed,adamgreen/mbed,nRFMesh/mbed-os,nRFMesh/mbed-os,adamgreen/mbed,bcostm/mbed-os,karsev/mbed-os,HeadsUpDisplayInc/mbed,mikaleppanen/mbed-os,ryankurte/mbed-os,adamgreen/mbed,andcor02/mbed-os,theotherjimmy/mbed,j-greffe/mbed-os,ryankurte/mbed-os,pradeep-gr/mbed-os5-onsemi,mikaleppanen/mbed-os,svogl/mbed-os,pradeep-gr/mbed-os5-onsemi,mazimkhan/mbed-os,CalSol/mbed,karsev/mbed-os,svogl/mbed-os,betzw/mbed-os,nRFMesh/mbed-os,CalSol/mbed,cvtsi2sd/mbed-os,fanghuaqi/mbed,adamgreen/mbed,cvtsi2sd/mbed-os,kl-cruz/mbed-os,adustm/mbed,c1728p9/mbed-os,cvtsi2sd/mbed-os,infinnovation/mbed-os,theotherjimmy/mbed,bcostm/mbed-os,Archcady/mbed-os,screamerbg/mbed,catiedev/mbed-os,pradeep-gr/mbed-os5-onsemi,kjbracey-arm/mbed,mbedmicro/mbed,Archcady/mbed-os,mmorenobarm/mbed-os,fahhem/mbed-os,mikaleppanen/mbed-os,mmorenobarm/mbed-os,svogl/mbed-os,fahhem/mbed-os,karsev/mbed-os,netzimme/mbed-os,fanghuaqi/mbed,HeadsUpDisplayInc/mbed,netzimme/mbed-os,pradeep-gr/mbed-os5-onsemi,YarivCol/mbed-os,bulislaw/mbed-os,nvlsianpu/mbed,radhika-raghavendran/mbed-os5.1-onsemi,c1728p9/mbed-os,c1728p9/mbed-os,kjbracey-arm/mbed,YarivCol/mbed-os,bulislaw/mbed-os,j-greffe/mbed-os,adustm/mbed,ryankurte/mbed-os,bulislaw/mbed-os,mbedmicro/mbed,monkiineko/mbed-os,nvlsianpu/mbed,Archcady/mbed-os,bcostm/mbed-os,bcostm/mbed-os,andcor02/mbed-os,theotherjimmy/mbed,mikaleppanen/mbed-os,mmorenobarm/mbed-os,monkiineko/mbed-os,mbedmicro/mbed,arostm/mbed-os,netzimme/mbed-os,ryankurte/mbed-os,betzw/mbed-os,NXPmicro/mbed,NXPmicro/mbed,betzw/mbed-os,radhika-raghavendran/mbed-os5.1-onsemi,svogl/mbed-os,NXPmicro/mbed,arostm/mbed-os,betzw/mbed-os,adustm/mbed,CalSol/mbed,c1728p9/mbed-os,netzimme/mbed-os,nRFMesh/mbed-os,screamerbg/mbed,arostm/mbed-os,HeadsUpDisplayInc/mbed,arostm/mbed-os,mazimkhan/mbed-os,RonEld/mbed,ryankurte/mbed-os,karsev/mbed-os,fahhem/mbed-os,andcor02/mbed-os,NXPmicro/mbed,fanghuaqi/mbed,catiedev/mbed-os,radhika-raghavendran/mbed-os5.1-onsemi,radhika-raghavendran/mbed-os5.1-onsemi,RonEld/mbed,mmorenobarm/mbed-os,nvlsianpu/mbed,ryankurte/mbed-os,mbedmicro/mbed,c1728p9/mbed-os,catiedev/mbed-os,fahhem/mbed-os,Archcady/mbed-os,fahhem/mbed-os,HeadsUpDisplayInc/mbed,mbedmicro/mbed,mazimkhan/mbed-os,fanghuaqi/mbed,monkiineko/mbed-os,netzimme/mbed-os,kl-cruz/mbed-os,bcostm/mbed-os,monkiineko/mbed-os,HeadsUpDisplayInc/mbed,RonEld/mbed,betzw/mbed-os,mazimkhan/mbed-os,HeadsUpDisplayInc/mbed,Archcady/mbed-os,kjbracey-arm/mbed,arostm/mbed-os,svogl/mbed-os,monkiineko/mbed-os,kl-cruz/mbed-os,mmorenobarm/mbed-os,radhika-raghavendran/mbed-os5.1-onsemi,CalSol/mbed,cvtsi2sd/mbed-os,infinnovation/mbed-os,karsev/mbed-os,bulislaw/mbed-os,screamerbg/mbed,svogl/mbed-os,NXPmicro/mbed,RonEld/mbed,j-greffe/mbed-os,cvtsi2sd/mbed-os,catiedev/mbed-os,screamerbg/mbed,pradeep-gr/mbed-os5-onsemi,YarivCol/mbed-os,cvtsi2sd/mbed-os,adustm/mbed,NXPmicro/mbed,andcor02/mbed-os,mmorenobarm/mbed-os,adustm/mbed,infinnovation/mbed-os,adamgreen/mbed,RonEld/mbed,arostm/mbed-os,mazimkhan/mbed-os,Archcady/mbed-os,catiedev/mbed-os,adamgreen/mbed,nvlsianpu/mbed,pradeep-gr/mbed-os5-onsemi,fanghuaqi/mbed,screamerbg/mbed,bulislaw/mbed-os,theotherjimmy/mbed,infinnovation/mbed-os,j-greffe/mbed-os,nRFMesh/mbed-os,YarivCol/mbed-os,YarivCol/mbed-os,RonEld/mbed,betzw/mbed-os,andcor02/mbed-os,theotherjimmy/mbed,j-greffe/mbed-os,CalSol/mbed,mikaleppanen/mbed-os,fahhem/mbed-os,nRFMesh/mbed-os,mazimkhan/mbed-os,catiedev/mbed-os,infinnovation/mbed-os,netzimme/mbed-os,c1728p9/mbed-os,radhika-raghavendran/mbed-os5.1-onsemi,kl-cruz/mbed-os,j-greffe/mbed-os,bulislaw/mbed-os,kl-cruz/mbed-os,theotherjimmy/mbed,CalSol/mbed,YarivCol/mbed-os