Re-enable building position-independent executables on Linux/*BSD

This provides better security at the cost of having misleading
binary icons on some file managers.

Now that recent Linux distributions no longer allow executing
binaries by double-clicking them in a file manager (even if the
binary is set to be executable), the usability cost of PIE is lowered.
You have to use a terminal or install a `.desktop` file nowadays.

platform/linuxbsd/detect.py

@@ -201,11 +201,6 @@ def configure(env):
     env.Append(CCFLAGS=["-pipe"])
     env.Append(LINKFLAGS=["-pipe"])
 
-    # -fpie and -no-pie is supported on GCC 6+ and Clang 4+, both below our
-    # minimal requirements.
-    env.Append(CCFLAGS=["-fpie"])
-    env.Append(LINKFLAGS=["-no-pie"])
-
     ## Dependencies
 
     env.ParseConfig("pkg-config x11 --cflags --libs")