*-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/bintools-wrapper/add-flags.sh

@@ -1,32 +1,32 @@
 # See cc-wrapper for comments.
 var_templates_list=(
-    NIX+IGNORE_LD_THROUGH_GCC
-    NIX+LDFLAGS
-    NIX+LDFLAGS_BEFORE
-    NIX+LDFLAGS_AFTER
-    NIX+LDFLAGS_HARDEN
-    NIX+HARDENING_ENABLE
+    NIX_IGNORE_LD_THROUGH_GCC
+    NIX_LDFLAGS
+    NIX_LDFLAGS_BEFORE
+    NIX_LDFLAGS_AFTER
+    NIX_LDFLAGS_HARDEN
+    NIX_HARDENING_ENABLE
 )
 var_templates_bool=(
-    NIX+SET_BUILD_ID
-    NIX+DONT_SET_RPATH
+    NIX_SET_BUILD_ID
+    NIX_DONT_SET_RPATH
 )
 
 accumulateRoles
 
 for var in "${var_templates_list[@]}"; do
-    mangleVarList "$var" ${role_infixes[@]+"${role_infixes[@]}"}
+    mangleVarList "$var" ${role_suffixes[@]+"${role_suffixes[@]}"}
 done
 for var in "${var_templates_bool[@]}"; do
-    mangleVarBool "$var" ${role_infixes[@]+"${role_infixes[@]}"}
+    mangleVarBool "$var" ${role_suffixes[@]+"${role_suffixes[@]}"}
 done
 
 if [ -e @out@/nix-support/libc-ldflags ]; then
-    NIX_@infixSalt@_LDFLAGS+=" $(< @out@/nix-support/libc-ldflags)"
+    NIX_LDFLAGS_@suffixSalt@+=" $(< @out@/nix-support/libc-ldflags)"
 fi
 
 if [ -e @out@/nix-support/libc-ldflags-before ]; then
-    NIX_@infixSalt@_LDFLAGS_BEFORE="$(< @out@/nix-support/libc-ldflags-before) $NIX_@infixSalt@_LDFLAGS_BEFORE"
+    NIX_LDFLAGS_BEFORE_@suffixSalt@="$(< @out@/nix-support/libc-ldflags-before) $NIX_LDFLAGS_BEFORE_@suffixSalt@"
 fi
 
-export NIX_BINTOOLS_WRAPPER_@infixSalt@_FLAGS_SET=1
+export NIX_BINTOOLS_WRAPPER_FLAGS_SET_@suffixSalt@=1