[Bug c/69759] __builtin_alloca and __builtin_alloca_with_align undocumented

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69759
Bug 69759 depends on bug 69780, which changed state.

Bug 69780 Summary: [4.9/5/6 Regression] ICE on  __builtin_alloca_with_align 
with small alignment
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69780

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED