gcc: Fix cross after I accidentally changed build target

I deleted "bootstrap", but forgot to make the condition
build = host = target.

pkgs/development/compilers/gcc/4.8/default.nix

@@ -208,7 +208,7 @@ stdenv.mkDerivation ({
   targetConfig = if targetPlatform != hostPlatform then targetPlatform.config else null;
 
   buildFlags = optional
-    (hostPlatform == buildPlatform)
+    (targetPlatform == hostPlatform && hostPlatform == buildPlatform)
     (if profiledCompiler then "profiledbootstrap" else "bootstrap");
 
   dontStrip = !stripped;

pkgs/development/compilers/gcc/4.9/default.nix

@@ -214,7 +214,7 @@ stdenv.mkDerivation ({
   targetConfig = if targetPlatform != hostPlatform then targetPlatform.config else null;
 
   buildFlags = optional
-    (hostPlatform == buildPlatform)
+    (targetPlatform == hostPlatform && hostPlatform == buildPlatform)
     (if profiledCompiler then "profiledbootstrap" else "bootstrap");
 
   dontStrip = !stripped;

pkgs/development/compilers/gcc/5/default.nix

@@ -221,7 +221,7 @@ stdenv.mkDerivation ({
   targetConfig = if targetPlatform != hostPlatform then targetPlatform.config else null;
 
   buildFlags = optional
-    (hostPlatform == buildPlatform)
+    (targetPlatform == hostPlatform && hostPlatform == buildPlatform)
     (if profiledCompiler then "profiledbootstrap" else "bootstrap");
 
   dontStrip = !stripped;

pkgs/development/compilers/gcc/6/default.nix

@@ -223,7 +223,7 @@ stdenv.mkDerivation ({
   targetConfig = if targetPlatform != hostPlatform then targetPlatform.config else null;
 
   buildFlags = optional
-    (hostPlatform == buildPlatform)
+    (targetPlatform == hostPlatform && hostPlatform == buildPlatform)
     (if profiledCompiler then "profiledbootstrap" else "bootstrap");
 
   dontStrip = !stripped;

pkgs/development/compilers/gcc/7/default.nix

@@ -200,7 +200,7 @@ stdenv.mkDerivation ({
   targetConfig = if targetPlatform != hostPlatform then targetPlatform.config else null;
 
   buildFlags = optional
-    (hostPlatform == buildPlatform)
+    (targetPlatform == hostPlatform && hostPlatform == buildPlatform)
     (if profiledCompiler then "profiledbootstrap" else "bootstrap");
 
   dontStrip = !stripped;

pkgs/development/compilers/gcc/8/default.nix

@@ -184,7 +184,7 @@ stdenv.mkDerivation ({
   targetConfig = if targetPlatform != hostPlatform then targetPlatform.config else null;
 
   buildFlags = optional
-    (hostPlatform == buildPlatform)
+    (targetPlatform == hostPlatform && hostPlatform == buildPlatform)
     (if profiledCompiler then "profiledbootstrap" else "bootstrap");
 
   dontStrip = !stripped;

pkgs/development/compilers/gcc/9/default.nix

@@ -183,7 +183,7 @@ stdenv.mkDerivation ({
   targetConfig = if targetPlatform != hostPlatform then targetPlatform.config else null;
 
   buildFlags = optional
-    (hostPlatform == buildPlatform)
+    (targetPlatform == hostPlatform && hostPlatform == buildPlatform)
     (if profiledCompiler then "profiledbootstrap" else "bootstrap");
 
   dontStrip = !stripped;

pkgs/development/compilers/gcc/snapshot/default.nix

@@ -155,7 +155,7 @@ stdenv.mkDerivation ({
   targetConfig = if targetPlatform != hostPlatform then targetPlatform.config else null;
 
   buildFlags = optional
-    (hostPlatform == buildPlatform)
+    (targetPlatform == hostPlatform && hostPlatform == buildPlatform)
     (if profiledCompiler then "profiledbootstrap" else "bootstrap");
 
   dontStrip = !stripped;