added flgas for conditional compilation of available backends

package.yaml

@@ -19,6 +19,24 @@ extra-source-files:
 # common to point users to the README.md file.
 description:         Please see the README on GitHub at <https://github.com/githubuser/tickLeisteServer#readme>
 
+flags:
+  http:
+    description: Build with http support
+    manual: true
+    default: true
+  https:
+    description: Build with https support
+    manual: true
+    default: false
+  fast-cgi:
+    description: Build with fastcgi support
+    manual: true
+    default: false
+  cgi:
+    description: Build with cgi support
+    manual: true
+    default: false
+
 dependencies:
 - base >= 4.7 && < 5
 - tickLeiste
@@ -31,8 +49,12 @@ dependencies:
 - containers
 - wai
 - wai-websockets
-- http-types
-- warp
+
+when:
+  - condition: flag(http)
+    dependencies:
+    - http-types
+    - warp
 
 build-tools:
 - cpphs