Auto merge of #568 - anatol:add_MINSIGSTKSZ, r=alexcrichton

Add MINSIGSTKSZ constant to linux sources

MINSIGSTKSZ is a minimum size of process stack allowed
diff --git a/appveyor.yml b/appveyor.yml
index 403682a..b6c666c 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -7,7 +7,7 @@
   - TARGET: x86_64-pc-windows-msvc
   - TARGET: i686-pc-windows-msvc
 install:
-  - appveyor DownloadFile https://win.rustup.rs/ -FileName rustup-init.exe
+  - appveyor-retry appveyor DownloadFile https://win.rustup.rs/ -FileName rustup-init.exe
   - rustup-init.exe -y --default-host %TARGET%
   - set PATH=%PATH%;C:\Users\appveyor\.cargo\bin
   - if defined MSYS2_BITS set PATH=%PATH%;C:\msys64\mingw%MSYS2_BITS%\bin