Keep build files in sync (Port bug 1430036: Don't set PKG_CONFIG_LIBDIR when building on Debian). rs=bustage-fix

build/unix/mozconfig.linux

@@ -26,5 +26,7 @@ fi
 
 . "$topsrcdir/build/unix/mozconfig.stdcxx"
 
+if [ -f /etc/redhat-release ]; then
 # PKG_CONFIG_LIBDIR is appropriately overridden in mozconfig.linux32
 export PKG_CONFIG_LIBDIR=/usr/local/lib64/pkgconfig:/usr/lib64/pkgconfig:/usr/share/pkgconfig
+fi

build/unix/mozconfig.linux32

@@ -1,6 +1,8 @@
 . "$topsrcdir/build/unix/mozconfig.linux"
 
+if [ -f /etc/redhat-release ]; then
 export PKG_CONFIG_LIBDIR=/usr/local/lib/pkgconfig:/usr/lib/pkgconfig:/usr/share/pkgconfig
+fi
 
 export MOZ_LINUX_32_SSE2_STARTUP_ERROR=1