chore: import upstream snapshot with attribution

third_party/fft2d/fft2d.BUILD

@@ -0,0 +1,45 @@
+# 2D Fast Fourier Transform package
+# from http://momonga.t.u-tokyo.ac.jp/~ooura/fft2d.html
+
+package(
+    default_visibility = ["//visibility:public"],
+)
+
+# Unrestricted use; can only distribute original package.
+licenses(["notice"])
+
+exports_files(["readme2d.txt"])
+
+FFT2D_SRCS = [
+    "fftsg.c",
+    "fftsg2d.c",
+]
+
+config_setting(
+    name = "windows",
+    values = {"cpu": "x64_windows"},
+)
+
+# This is the main 2D FFT library.  The 2D FFTs in this library call
+# 1D FFTs.  In addition, fast DCTs are provided for the special case
+# of 8x8 and 16x16.  This code in this library is referred to as
+# "Version II" on http://momonga.t.u-tokyo.ac.jp/~ooura/fft2d.html.
+cc_library(
+    name = "fft2d",
+    srcs = FFT2D_SRCS,
+    linkopts = select({
+        ":windows": [],
+        "//conditions:default": ["-lm"],
+    }),
+)
+
+objc_library(
+    name = "fft2d_ios",
+    srcs = FFT2D_SRCS,
+)
+
+# Export the source code so that it could be compiled for Andoid native apps.
+filegroup(
+    name = "fft2d_srcs",
+    srcs = FFT2D_SRCS,
+)