treewide: NIX_*_FLAGS -> string

pkgs/development/libraries/libcbor/default.nix

@@ -16,7 +16,7 @@ stdenv.mkDerivation rec {
 
   doCheck = false; # needs "-DWITH_TESTS=ON", but fails w/compilation error
 
-  NIX_CFLAGS_COMPILE = [ "-fno-lto" ];
+  NIX_CFLAGS_COMPILE = "-fno-lto";
 
   meta = with stdenv.lib; {
     description = "CBOR protocol implementation for C and others";

pkgs/development/libraries/libdynd/default.nix

@@ -17,7 +17,7 @@ stdenv.mkDerivation {
   ];
 
   # added to fix build with gcc7+
-  NIX_CFLAGS_COMPILE = [
+  NIX_CFLAGS_COMPILE = builtins.toString [
     "-Wno-error=implicit-fallthrough"
     "-Wno-error=nonnull"
     "-Wno-error=tautological-compare"

pkgs/development/libraries/libfakekey/default.nix

@@ -11,9 +11,7 @@ stdenv.mkDerivation rec {
 
   nativeBuildInputs = [ pkgconfig ];
   buildInputs = [ libX11 libXi libXtst xorgproto ];
-  NIX_LDFLAGS = [
-    "-lX11"
-  ];
+  NIX_LDFLAGS = "-lX11";
 
   meta = with stdenv.lib; {
     description = "X virtual keyboard library";

pkgs/development/libraries/libfpx/default.nix

@@ -9,7 +9,7 @@ stdenv.mkDerivation rec {
   };
 
   # Darwin gets misdetected as Windows without this
-  NIX_CFLAGS_COMPILE = if stdenv.isDarwin then "-D__unix" else null;
+  NIX_CFLAGS_COMPILE = stdenv.lib.optionalString stdenv.isDarwin "-D__unix";
 
   patches = [
     (fetchpatch {

pkgs/development/libraries/libmatchbox/default.nix

@@ -6,9 +6,7 @@ stdenv.mkDerivation rec {
 
   buildInputs = [ libXft libICE pango libjpeg ];
   propagatedBuildInputs = [ libX11 libXext libpng ];
-  NIX_LDFLAGS = [
-    "-lX11"
-  ];
+  NIX_LDFLAGS = "-lX11";
 
   src = fetchurl {
     url = "https://downloads.yoctoproject.org/releases/matchbox/libmatchbox/${version}/libmatchbox-${version}.tar.bz2";

pkgs/development/libraries/libwps/default.nix

@@ -12,7 +12,7 @@ stdenv.mkDerivation rec {
   nativeBuildInputs = [ pkgconfig ];
   buildInputs = [ boost librevenge zlib ];
 
-  NIX_CFLAGS_COMPILE = [ "-Wno-error=implicit-fallthrough" ]; # newly detected by gcc-7
+  NIX_CFLAGS_COMPILE = "-Wno-error=implicit-fallthrough";
 
   meta = with stdenv.lib; {
     homepage = http://libwps.sourceforge.net/;

pkgs/development/libraries/mediastreamer/default.nix

@@ -32,7 +32,7 @@ stdenv.mkDerivation rec {
     ortp libv4l libpcap srtp bctoolbox libXext libmatroska
   ];
 
-  NIX_CFLAGS_COMPILE = [
+  NIX_CFLAGS_COMPILE = toString [
     "-DGIT_VERSION=\"v${version}\""
     "-Wno-error=deprecated-declarations"
     "-Wno-error=cast-function-type"

pkgs/development/libraries/mlt/qt-5.nix

@@ -33,7 +33,7 @@ stdenv.mkDerivation rec {
 
   # mlt is unable to cope with our multi-prefix Qt build
   # because it does not use CMake or qmake.
-  NIX_CFLAGS_COMPILE = [ "-I${getDev qtsvg}/include/QtSvg" ];
+  NIX_CFLAGS_COMPILE = "-I${getDev qtsvg}/include/QtSvg";
 
   CXXFLAGS = "-std=c++11";
 

pkgs/development/libraries/xmlsec/default.nix

@@ -27,7 +27,7 @@ stdenv.mkDerivation {
   configureFlags = [ "--enable-soap" ];
 
   # otherwise libxmlsec1-gnutls.so won't find libgcrypt.so, after #909
-  NIX_LDFLAGS = [ "-lgcrypt" ];
+  NIX_LDFLAGS = "-lgcrypt";
 
   postInstall = ''
     moveToOutput "bin/xmlsec1-config" "$dev"