Revert "CDRIVER-2188 Bump evergreen to macos-1012 as osx-1010 is being decomissioned"

This reverts commit 997a823.

This commit only solved some of the problem, not all

Author: bjori

.evergreen/compile-unix.sh

@@ -202,7 +202,7 @@ case "$OS" in
       CFLAGS="$CFLAGS -Wno-unknown-pragmas"
       export DYLD_LIBRARY_PATH=".libs:src/libbson/.libs:$LD_LIBRARY_PATH"
       # llvm-cov is installed from brew
-      export PATH=$PATH:/usr/local/opt/llvm/bin
+      export PATH=/usr/local/opt/llvm/bin:$PATH
    ;;
 
    linux)

.evergreen/config.yml

@@ -6799,11 +6799,11 @@ buildvariants:
       # We don't have i386 builds of OpenSSL or Cyrus SASL installed
 
 - name: darwin
-  display_name: "*Darwin, macOS (Apple LLVM)"
+  display_name: "*Darwin, OS X (Apple LLVM)"
   expansions:
     CC: "clang"
   run_on:
-    - macos-1012
+    - osx-1010
   tasks:
     - "debug-compile-coverage"
     - "release-compile"