Exit on failure in rundiff.sh.

In particular, don't show a diff created with an old binary if
linkerconfig failed to compile.

Test: system/linkerconfig/rundiff.sh
  (with and without a syntax error in a linkerconfig .cc file)
Bug: 140599044
Change-Id: I1449de75d20e8a40f26bac087048f869a0f468a5
1 file changed