Fix g++ linking error.

Fix g++ linking error.

The linking errors are the following.  Somehow the clang build succeeds.

.../IceInstARM32.o:IceInstARM32.cpp:(.text$_ZNK3Ice5ARM3220InstARM32ThreeAddrFPILNS0_9InstARM3213InstKindARM32E74EE4dumpEPKNS_3CfgE[__ZNK3Ice5ARM3220InstARM32ThreeAddrFPILNS0_9InstARM3213InstKindARM32E74EE4dumpEPKNS_3CfgE]+0x38): undefined reference to `Ice::ARM32::InstARM32ThreeAddrFP<(Ice::ARM32::InstARM32::InstKindARM32)74>::Opcode'
.../IceInstARM32.o:IceInstARM32.cpp:(.text$_ZNK3Ice5ARM3220InstARM32ThreeAddrFPILNS0_9InstARM3213InstKindARM32E75EE4dumpEPKNS_3CfgE[__ZNK3Ice5ARM3220InstARM32ThreeAddrFPILNS0_9InstARM3213InstKindARM32E75EE4dumpEPKNS_3CfgE]+0x38): undefined reference to `Ice::ARM32::InstARM32ThreeAddrFP<(Ice::ARM32::InstARM32::InstKindARM32)75>::Opcode'
collect2.exe: error: ld returned 1 exit status

BUG= none
TBR=jpp

Review URL: https://codereview.chromium.org/1576823002 .