stack/slapos-py2.cfg: Pin gcc to gcc-8.5 for scipy

Remove

```
[gcc:python2]
part = gcc-8.5
```

from neoppod/software-common.cfg and dream/software.cfg as it causes
gcc being pinned to a different version before and after rebootstrap
when the initial python version is not Python2.

This reverts dc91e5d4.

software/dream/software.cfg

@@ -21,10 +21,6 @@ parts =
 # Always build GCC for Fortran (see openblas).
 max_version = 0
 
-[gcc:python2]
-# also use old gcc version for old scipy version used in python2
-part = gcc-8.5
-
 [dream-repository.git]
 revision = f3bcf115741886835df8c0ca0fdbf510d77d8db8
 

software/neoppod/software-common.cfg

@@ -30,10 +30,6 @@ parts =
     neoppod
     slapos-cookbook
 
-[gcc:python2]
-# use old gcc version for old scipy version used in python2
-part = gcc-8.5
-
 [neoppod-repository]
 recipe = slapos.recipe.build:gitclone
 repository = https://lab.nexedi.com/nexedi/neoppod.git

stack/slapos-py2.cfg

@@ -4,6 +4,10 @@ extends = slapos.cfg
 [python]
 part = python2.7
 
+[gcc]
+# To compile Python2-compatible scipy==1.0.1
+part = gcc-8.5
+
 [openssl]
 <= openssl-1.1