account for build_only deps

conda/migrate.py

@@ -15,6 +15,11 @@ RUN_EXPORTS = [
     '    - libblitz\n',
 ]
 
+BUILD_ONLY_DEPS = [
+    '    - pkg-config {{ pkg_config }}\n',
+    '    - cmake {{ cmake }}\n',
+]
+
 
 def extract_requirements_text(path):
   text = ""
@@ -111,21 +116,23 @@ def migrate(template_recipe_path, old_recipe_path, build_variant_path,
       "- {{ compiler('c') }}\n",
       "- {{ compiler('cxx') }}\n",
   ]
-  requires_compilers = 'toolchain' in host_text or build_text
   for line in already_build:
     host_text = host_text.replace(line, '')
   host_text = host_text.strip()
   if host_text:
     host_text = '    ' + host_text + '\n'
     host_text = add_variant(host_text, star=False)
+  # normalize build_text
+  build_text = build_text.rstrip()
+  if build_text:
+    build_text = '  build:\n' + build_text + '\n'
+  # remove BUILD_ONLY_DEPS from host and put it in build_text
+  for p in BUILD_ONLY_DEPS:
+    if p in host_text:
+      host_text = host_text.replace(p, '')
+      build_text += p
   final_recipe = final_recipe.replace('    <HOST_DEPS>\n', host_text)
-  if requires_compilers:
-    final_recipe = final_recipe.replace('  <BUILD_DEPS>\n', '''  build:
-    - {{ compiler('c')}}
-    - {{ compiler('cxx')}}
-''')
-  else:
-    final_recipe = final_recipe.replace('  <BUILD_DEPS>\n', '')
+  final_recipe = final_recipe.replace('  <BUILD_DEPS>\n', build_text)
 
   run_text = requirements_text[i2 + 5:]
   for line in already_build[:2] + RUN_EXPORTS: