Disable satisfied-skip-solve on 32-bit linux

The default install of Conda on 32 bit linux uses repo.anaconda.com/miniconda; those 32 bit builds are very dated and so do not support the --satisfied-skip-solve flag

The latest 32 bit linux build (https://repo.anaconda.com/miniconda/Miniconda3-latest-Linux-x86.sh) is 4.5.12, which pre-dates the introduction of --satisfied-skip-solve, which was introduced in 4.6.0 (https://docs.conda.io/projects/conda/en/latest/release-notes.html\#version-4.6.0).

This is a somewhat draconian approach, as someone could have a newer build of Conda on a 32 bit linux system, and this change prevents them from using --satisfied-skip-solve.

Even so, I think this change is worthwhile because (a) the current state means a default install of PyCall (which sets this flag) on 32 bit linux fails (b) preventing --satisfied-skip-solve does not change correctness, just performance (c) there are probably not a lot of people hitting this code path.

Author: angusmoore

src/Conda.jl

@@ -329,12 +329,25 @@ function add(pkg::PkgOrPkgs, env::Environment=ROOTENV;
              args::Cmd = ``,
             )
     c = isempty(channel) ? `` : `-c $channel`
-    @static if Sys.iswindows() && Sys.WORD_SIZE == 32
+    @static if (Sys.iswindows() || Sys.islinux()) && Sys.WORD_SIZE == 32
         if satisfied_skip_solve
-            @warn """
-            The keyword satisfied_skip_solve was set to true,
-            but conda does not support --satisfied-skip-resolve on 32-bit Windows.
-            """
+            if Sys.iswindows()
+                @warn """
+                The keyword satisfied_skip_solve was set to true,
+                but conda does not support --satisfied-skip-resolve on 32-bit Windows.
+                """
+            else
+                # --satisfied-skip-solve flag was introduced in Conda 4.6.0
+                # https://docs.conda.io/projects/conda/en/latest/release-notes.html#version-4.6.0
+                # 32 bit builds on https://repo.anaconda.com/miniconda/ (where non-
+                # miniconda builds are by default sourced from) have not been updated since
+                # 4.5.12 for Linux-x86
+                @warn """
+                The keyword satisfied_skip_solve was set to true, but Conda builds
+                for 32 bit are (by default) quite old and do not support this
+                --satisfied-skip-resolve.
+                """
+            end
         end
         S = ``
     else