Remove curl references

Building-for-Linux.md

@@ -23,9 +23,6 @@ You'll need to download and install the following to build Citra:
 * [Clang](https://github.com/llvm-mirror/clang) 5.0 (optional build alternative) _This guide was written before we bumping the version to C++17, so please refill them below after testing._
   - ~~Deb: `apt-get install clang libc++-dev` (in some distros, clang-5.0).~~
   - ~~Arch: `pacman -S clang`, `libc++` is in the AUR. Use pacaur or yaourt to install it.~~
-* Curl
-  - Deb: `apt-get install libcurl4-openssl-dev`
-  - Arch `pacman -S libcurl-compat`
 * Note on Boost library: you don't need to install Boost library on your system, because citra provides a bundled trimmed Boost library. However, if you already have Boost library installed on your system, please make sure its version is at least 1.66 (which contains a bug fix for GCC 7), otherwise compilation would fail.
 
 ### Cloning Citra in Git:
@@ -43,7 +40,7 @@ The `--recursive` option automatically clones the required Git submodules too.
 
 ```
 mkdir build && cd build
-cmake ../ -DUSE_SYSTEM_CURL=1
+cmake ../
 make
 sudo make install
 ```