*-wrapper; Switch from infixSalt to suffixSalt

I hate the thing too even though I made it, and rather just get rid of
it. But we can't do that yet. In the meantime, this brings us more
inline with autoconf and will make it slightly easier for me to write a
pkg-config wrapper, which we need.

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

@@ -6,9 +6,9 @@
 # tools. For example:
 #
 #   # Flags for compiling (whether or not linking) C code for the...
-#   NIX_BUILD_CFLAGS_COMPILE  # ...build platform
-#   NIX_CFLAGS_COMPILE        # ...host platform
-#   NIX_TARGET_CFLAGS_COMPILE # ...target platform
+#   NIX_CFLAGS_COMPILE_FOR_BUILD  # ...build platform
+#   NIX_CFLAGS_COMPILE            # ...host platform
+#   NIX_CFLAGS_COMPILE_FOR_TARGET # ...target platform
 #
 # Notice that these platforms are the 3 *relative* to the package using
 # cc-wrapper, not absolute like `x86_64-pc-linux-gnu`.
@@ -33,12 +33,12 @@
 # The basic strategy is:
 #
 #  - Everyone exclusively *adds information* to relative-platform-specific
-#    environment variables, like `NIX_TARGET_CFLAGS_COMPILE`, to communicate
+#    environment variables, like `NIX_CFLAGS_COMPILE_FOR_TARGET`, to communicate
 #    with the wrapped binaries.
 #
 #  - The wrapped binaries will exclusively *read* cc-wrapper-derivation-specific
-#    environment variables distinguished with with `infixSalt`, like
-#    `NIX_@infixSalt@_CFLAGS_COMPILE`.
+#    environment variables distinguished with with `suffixSalt`, like
+#    `NIX_CFLAGS_COMPILE_@suffixSalt@`.
 #
 #  - `add-flags`, beyond its old task of reading extra flags stuck inside the
 #    cc-wrapper derivation, will convert the relative-platform-specific
@@ -65,15 +65,15 @@
 # function is guaranteed to be exactly the same.
 ccWrapper_addCVars () {
     # See ../setup-hooks/role.bash
-    local role_post role_pre
+    local role_post
     getHostRoleEnvHook
 
     if [ -d "$1/include" ]; then
-        export NIX_${role_pre}CFLAGS_COMPILE+=" -isystem $1/include"
+        export NIX_CFLAGS_COMPILE${role_post}+=" -isystem $1/include"
     fi
 
     if [ -d "$1/Library/Frameworks" ]; then
-        export NIX_${role_pre}CFLAGS_COMPILE+=" -iframework $1/Library/Frameworks"
+        export NIX_CFLAGS_COMPILE${role_post}+=" -iframework $1/Library/Frameworks"
     fi
 }
 
@@ -105,10 +105,10 @@ fi
 
 # Export tool environment variables so various build systems use the right ones.
 
-export NIX_${role_pre}CC=@out@
+export NIX_CC${role_post}=@out@
 
-export ${role_pre}CC=@named_cc@
-export ${role_pre}CXX=@named_cxx@
+export CC${role_post}=@named_cc@
+export CXX${role_post}=@named_cxx@
 export CC${role_post}=@named_cc@
 export CXX${role_post}=@named_cxx@
 
@@ -117,4 +117,4 @@ export CXX${role_post}=@named_cxx@
 export NIX_HARDENING_ENABLE
 
 # No local scope in sourced file
-unset -v role_pre role_post
+unset -v role_post