treewide: Use pkgs/build-support/roles.bash to remove copy pasta

Also fix some setup hooks that unnecessarily used environment hooks,
which revolted in the same variable being modified too many times.

pkgs/build-support/cc-wrapper/setup-hook.sh

@@ -66,55 +66,22 @@ set -u
 # over no state, and there's no @-substitutions within, so any redefined
 # function is guaranteed to be exactly the same.
 ccWrapper_addCVars () {
-    # The `depHostOffset` describes how the host platform of the dependencies
-    # are slid relative to the depending package. It is brought into scope of
-    # the environment hook defined as the role of the dependency being applied.
-    case $depHostOffset in
-        -1) local role='BUILD_' ;;
-        0)  local role='' ;;
-        1)  local role='TARGET_' ;;
-        *)  echo "cc-wrapper: Error: Cannot be used with $depHostOffset-offset deps" >2;
-            return 1 ;;
-    esac
+    # See ../setup-hooks/role.bash
+    local role_post role_pre
+    getTargetRoleEnvHook
 
     if [[ -d "$1/include" ]]; then
-        export NIX_${role}CFLAGS_COMPILE+=" ${ccIncludeFlag:--isystem} $1/include"
+        export NIX_${role_pre}CFLAGS_COMPILE+=" ${ccIncludeFlag:--isystem} $1/include"
     fi
 
     if [[ -d "$1/Library/Frameworks" ]]; then
-        export NIX_${role}CFLAGS_COMPILE+=" -F$1/Library/Frameworks"
+        export NIX_${role_pre}CFLAGS_COMPILE+=" -F$1/Library/Frameworks"
     fi
 }
 
-# Since the same cc-wrapper derivation can be depend on in multiple ways, we
-# need to accumulate *each* role (i.e. target platform relative the depending
-# derivation) in which the cc-wrapper derivation is used.
-# `NIX_CC_WRAPPER_@infixSalt@_TARGET_*` tracks this (needs to be an exported env
-# var so can't use fancier data structures).
-#
-# We also need to worry about what role is being added on *this* invocation of
-# setup-hook, which `role` tracks.
-case $targetOffset in
-    -1)
-        export NIX_CC_WRAPPER_@infixSalt@_TARGET_BUILD=1
-        role_pre='BUILD_'
-        role_post='_FOR_BUILD'
-        ;;
-    0)
-        export NIX_CC_WRAPPER_@infixSalt@_TARGET_HOST=1
-        role_pre=''
-        role_post=''
-        ;;
-    1)
-        export NIX_CC_WRAPPER_@infixSalt@_TARGET_TARGET=1
-        role_pre='TARGET_'
-        role_post='_FOR_TARGET'
-        ;;
-    *)
-        echo "cc-wrapper: used as improper sort of dependency" >2;
-        return 1
-        ;;
-esac
+# See ../setup-hooks/role.bash
+getTargetRole
+getTargetRoleWrapper
 
 # We use the `targetOffset` to choose the right env hook to accumulate the right
 # sort of deps (those with that offset).