Remove legacy backend

tests/getheader.nims

@@ -14,7 +14,7 @@ proc testCall(cmd, output: string, exitCode: int, delete = true) =
   doAssert outp.contains(output), outp
 
 var
-  cmd = "nim c -f --hints:off -d:FLAGS=\"-f:ast2\" -d:checkAbi"
+  cmd = "nim c -f --hints:off -d:checkAbi"
   lrcmd = " -r lzma.nim"
   zrcmd = " -r zlib.nim"
   sshcmd = " -r libssh2.nim"

tests/libssh2.nim

@@ -17,12 +17,12 @@ cOverride:
     SOCKET = object
 
 when not libssh2Static:
-  cImport(libssh2Path, recurse = true, dynlib = "libssh2LPath", flags = "-f:ast2 -c -E_ -F_")
+  cImport(libssh2Path, recurse = true, dynlib = "libssh2LPath", flags = "-c -E_ -F_")
 
   when not defined(Windows) and not isDefined(libssh2JBB):
     proc zlibVersion(): cstring {.importc, dynlib: libssh2LPath.}
 else:
-  cImport(libssh2Path, recurse = true, flags = "-f:ast2 -c -E_ -F_")
+  cImport(libssh2Path, recurse = true, flags = "-c -E_ -F_")
 
   when not defined(Windows) and not isDefined(libssh2JBB):
     proc zlibVersion(): cstring {.importc.}

tests/rsa.nim

@@ -39,7 +39,7 @@ cOverride:
 cImport(@[
   basePath / "rsa.h",
   basePath / "err.h",
-], recurse = true, flags = "-f:ast2 -s -c " & FLAGS)
+], recurse = true, flags = "-s -c " & FLAGS)
 
 {.passL: cryptoLPath.}