Loader: Handle bad section names when loading an ELF file.
Loader: Handle bad section names when loading an ELF file.

If there's a problem when reading the section names from a supposed ELF file,
this change makes gem5 print an error message as returned by libelf and die.
Previously these sorts of errors would make gem5 segfault when it tried to
access the section name through a NULL pointer.

joerocklin/gem5,powerjg/gem5-ci-test,KuroeKurose/gem5,kaiyuanl/gem5,rallylee/gem5,Weil0ng/gem5,yb-kim/gemV,zlfben/gem5,KuroeKurose/gem5,rallylee/gem5,HwisooSo/gemV-update,kaiyuanl/gem5,yb-kim/gemV,gedare/gem5,TUD-OS/gem5-dtu,briancoutinho0905/2dsampling,powerjg/gem5-ci-test,sobercoder/gem5,HwisooSo/gemV-update,aclifton/cpeg853-gem5,yb-kim/gemV,briancoutinho0905/2dsampling,kaiyuanl/gem5,Weil0ng/gem5,KuroeKurose/gem5,zlfben/gem5,gedare/gem5,briancoutinho0905/2dsampling,KuroeKurose/gem5,qizenguf/MLC-STT,KuroeKurose/gem5,Weil0ng/gem5,gedare/gem5,qizenguf/MLC-STT,qizenguf/MLC-STT,gem5/gem5,markoshorro/gem5,rjschof/gem5,rallylee/gem5,cancro7/gem5,rjschof/gem5,austinharris/gem5-riscv,rallylee/gem5,gedare/gem5,rjschof/gem5,SanchayanMaity/gem5,samueldotj/TeeRISC-Simulator,powerjg/gem5-ci-test,samueldotj/TeeRISC-Simulator,joerocklin/gem5,markoshorro/gem5,yb-kim/gemV,Weil0ng/gem5,qizenguf/MLC-STT,TUD-OS/gem5-dtu,joerocklin/gem5,powerjg/gem5-ci-test,qizenguf/MLC-STT,markoshorro/gem5,cancro7/gem5,yb-kim/gemV,rjschof/gem5,gem5/gem5,yb-kim/gemV,HwisooSo/gemV-update,rallylee/gem5,TUD-OS/gem5-dtu,cancro7/gem5,rallylee/gem5,Weil0ng/gem5,SanchayanMaity/gem5,austinharris/gem5-riscv,cancro7/gem5,HwisooSo/gemV-update,aclifton/cpeg853-gem5,sobercoder/gem5,powerjg/gem5-ci-test,austinharris/gem5-riscv,markoshorro/gem5,gedare/gem5,samueldotj/TeeRISC-Simulator,HwisooSo/gemV-update,markoshorro/gem5,sobercoder/gem5,sobercoder/gem5,markoshorro/gem5,rallylee/gem5,zlfben/gem5,samueldotj/TeeRISC-Simulator,zlfben/gem5,gedare/gem5,qizenguf/MLC-STT,samueldotj/TeeRISC-Simulator,cancro7/gem5,kaiyuanl/gem5,cancro7/gem5,samueldotj/TeeRISC-Simulator,briancoutinho0905/2dsampling,HwisooSo/gemV-update,austinharris/gem5-riscv,austinharris/gem5-riscv,TUD-OS/gem5-dtu,gem5/gem5,zlfben/gem5,SanchayanMaity/gem5,KuroeKurose/gem5,aclifton/cpeg853-gem5,TUD-OS/gem5-dtu,SanchayanMaity/gem5,joerocklin/gem5,rjschof/gem5,gem5/gem5,rjschof/gem5,SanchayanMaity/gem5,sobercoder/gem5,powerjg/gem5-ci-test,rjschof/gem5,qizenguf/MLC-STT,Weil0ng/gem5,aclifton/cpeg853-gem5,briancoutinho0905/2dsampling,yb-kim/gemV,kaiyuanl/gem5,gem5/gem5,zlfben/gem5,TUD-OS/gem5-dtu,powerjg/gem5-ci-test,Weil0ng/gem5,briancoutinho0905/2dsampling,austinharris/gem5-riscv,austinharris/gem5-riscv,joerocklin/gem5,joerocklin/gem5,aclifton/cpeg853-gem5,joerocklin/gem5,zlfben/gem5,aclifton/cpeg853-gem5,HwisooSo/gemV-update,samueldotj/TeeRISC-Simulator,SanchayanMaity/gem5,TUD-OS/gem5-dtu,sobercoder/gem5,KuroeKurose/gem5,SanchayanMaity/gem5,yb-kim/gemV,kaiyuanl/gem5,kaiyuanl/gem5,gem5/gem5,joerocklin/gem5,sobercoder/gem5,aclifton/cpeg853-gem5,gedare/gem5,gem5/gem5,briancoutinho0905/2dsampling,markoshorro/gem5,cancro7/gem5