[release-0.18] Segfault on Julia v0.6

[blegat]

Valgrind output: #1498 (comment)

Culprit PR: #1432
Cuplit commit of the PR:

• 56bea32 segfault
• 66425fa segfault
• 747adc6 segfault
• 40ba800 segfault
• 348f882 segfault
• 84640a7 segfault
• edd8534 segfault
• 811edc3 segfault
• b63ea7a MethodError
• 558cf85 generated function body is not pure. this likely means it contains a closure or comprehension.
• 217e8cb segfault generated function body is not pure. this likely means it contains a closure or comprehension.
• 503b104 generated function body is not pure. this likely means it contains a closure or comprehension.
• 402369a generated function body is not pure. this likely means it contains a closure or comprehension.
• 5138462 LoadError: UndefVarError: @warn not defined
• 6265a58 Success
• 7bee8ef

The "generated f.unction body is not pure. this likely means it contains a closure or comprehension." was fixed in b63ea7a.
This error prevents seeing from which the segfault starts to happen so I have rebased this commit earlier.

• 217e8cb segfault
• 503b104 MethodError for dot
• b63ea7a MethodError for dot and WARNING method definition overwritten
• 402369a

Seems to be between 503b104 and 217e8cb.
Let's cut 217e8cb in smaller chunks:

• 217e8cb
• dot changes MethodError for dot
• 503b104

[blegat]

It seems the cause is the change of 217e8cb
to parseExpr_staged.jl.
Since addtoexpr_reorder is a generated function and calls addtoexpr, the dot syntax in addtoexpr throws a segfault.
It seems related to JuliaLang/julia#19299 and JuliaLang/julia#21094

[blegat]

Closed by #1505