lld is crashing on some tests on the waterfall

[sbc100]

From the wasm waterfall:

https://wasm-stat.us/builders/linux/builds/25908

/b/build/slave/linux/build/src/src/work/wasm-install/bin/lld: error: /b/build/slave/linux/build/src/src/work/torture-o/O0/20070614-1.c.o: undefined symbol: __mulsc3
Similar unexpected failures, average 97.998046875% similarity with stddev 0.341796875: 20020108-1.c.o 20040709-1.c.o 20040709-2.c.o
Sample failure: FAILED 20020108-1.c.o
lld: /b/build/slave/linux/build/src/src/work/llvm/tools/lld/wasm/OutputSections.cpp:80: void applyRelocation(uint8_t *, const lld::wasm::OutputRelocation &): Assertion `decodeULEB128(Buf) == Reloc.Reloc.Index' failed.
/b/build/slave/linux/build/src/src/work/wasm-install/bin/../lib/libLLVM-6.0svn.so(+0x619524)[0x7ff9ece80524]
/b/build/slave/linux/build/src/src/work/wasm-install/bin/../lib/libLLVM-6.0svn.so(+0x619886)[0x7ff9ece80886]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x10330)[0x7ff9ef6b2330]
/lib/x86_64-linux-gnu/libc.so.6(gsignal+0x37)[0x7ff9ebcb4c37]
/lib/x86_64-linux-gnu/libc.so.6(abort+0x148)[0x7ff9ebcb8028]
/lib/x86_64-linux-gnu/libc.so.6(+0x2fbf6)[0x7ff9ebcadbf6]
/lib/x86_64-linux-gnu/libc.so.6(+0x2fca2)[0x7ff9ebcadca2]
/b/build/slave/linux/build/src/src/work/wasm-install/bin/lld[0x5f92c8]
/b/build/slave/linux/build/src/src/work/wasm-install/bin/lld[0x5f8c29]
/b/build/slave/linux/build/src/src/work/wasm-install/bin/lld[0x5f5cac]
/b/build/slave/linux/build/src/src/work/wasm-install/bin/../lib/libLLVM-6.0svn.so(+0x5bf065)[0x7ff9ece26065]
/b/build/slave/linux/build/src/src/work/wasm-install/bin/../lib/libLLVM-6.0svn.so(+0x5beb16)[0x7ff9ece25b16]
/usr/lib/x86_64-linux-gnu/libstdc++.so.6(+0xb1a60)[0x7ff9ec614a60]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x8184)[0x7ff9ef6aa184]
/lib/x86_64-linux-gnu/libc.so.6(clone+0x6d)[0x7ff9ebd7bffd]