Bug#833532: Rebuild against libicu57 causes icedove to crash

[Viktor Jägersküpper]

In case anyone is not able to use a version prior to 1:45.2.0-2+b1, and
since this version is in testing now, I tried a workaround and set
"javascript.options.baselinejit" to "false" in about:config. This worked
for me so far.