Segfault on debug bootstrap on armv7l

[staticfloat]

We're getting a segfault on make debug when running on armv7l:

signal (11): Segmentation fault
in expression starting at no file:0
_ZN4llvm15MCSymbolRefExprC1EPKNS_8MCSymbolENS0_11VariantKindEPKNS_9MCAsmInfoE at /buildworker/worker/package_linuxarmv7l/build/usr/bin/../lib/libLLVM-3.9.so (unknown line)
unknown function (ip: 0x8f64efa7)
Allocations: 226471069 (Pool: 226441832; Big: 29237); GC: 1332
Segmentation fault (core dumped)

See https://build.julialang.org/#/builders/4/builds/881 for more details. Interestingly enough, we make it through make release just fine. Perhaps our recent alignment fixes aren't getting applied properly to debug builds?

[vtjnash]

Seems to have been a std::bad_alloc up until https://build.julialang.org/#/builders/4/builds/616, but f9f11a3...12964e8 doesn't seem very interesting

[ViralBShah]

Maybe related to #26122