Revert "Reland "Reland "Add build file for PFFFT"""

This reverts commit a2fafd3.

Reason for revert: breaking ios-device-xcode-clang

TBR=thakis@chromium.org

Original change's description:
> Reland "Reland "Add build file for PFFFT""
>
> This is a reland of c1086af
>
> This CL fixes the compile issues of the reverted CL by defining M_LN2 when not defined.
>
> TBR=thakis@chromium.org
>
> Original change's description:
> > Reland "Add build file for PFFFT"
> >
> > This is a reland of 8e4cf15
> >
> > This CL includes the following changes:
> > 1. when fuzzing, PFFFT is compiled disabling SIMD
> > 2. SIMD is also disabled on fuchsia and android because PFFFT only checks __arm__
> > 3. unit test to validate the output of PFFFT (compared against that of FFTPACK)
> >
> > The first change fixes the problem due to which the original CL has been reverted;
> > however, it makes fuzzing slower and reduces the coverage since SIMD cannot be used.
> >
> > Similarly, the second change is a temporary solution to allow landing this CL.
> > SIMD will be re-enabled in a follow-up CL.
> >
> > Original change's description:
> > > Add build file for PFFFT
> > >
> > > - fuzzer corpus generator and fuzzer targets
> > > - fftpack isolated as private test only target (only needed for the benchmark)
> > >
> > > Bug: webrtc:9577
> > > Change-Id: Idc904bc4b05f945a7461a14893518551bbe34b84
> > > Reviewed-on: https://chromium-review.googlesource.com/c/1452000
> > > Commit-Queue: Ale Bzk <alessiob@chromium.org>
> > > Reviewed-by: Nico Weber <thakis@chromium.org>
> > > Reviewed-by: Olga Sharonova <olka@chromium.org>
> > > Reviewed-by: Max Moroz <mmoroz@chromium.org>
> > > Cr-Commit-Position: refs/heads/master@{#629627}
> >
> > Bug: webrtc:9577
> > Change-Id: Icfbb4b966c3ad866e9e2970b63363e0e258b1fea
> > Reviewed-on: https://chromium-review.googlesource.com/c/1458076
> > Commit-Queue: Ale Bzk <alessiob@chromium.org>
> > Reviewed-by: Nico Weber <thakis@chromium.org>
> > Reviewed-by: Max Moroz <mmoroz@chromium.org>
> > Reviewed-by: Max Morin <maxmorin@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#630085}
>
> Bug: webrtc:9577
> Change-Id: I6bfe6d5f103570cebb6ca7909bd0369ecd8a7c45
> Reviewed-on: https://chromium-review.googlesource.com/c/1460616
> Commit-Queue: Ale Bzk <alessiob@chromium.org>
> Reviewed-by: Olga Sharonova <olka@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#630278}

TBR=thakis@chromium.org,mmoroz@chromium.org,olka@chromium.org,maxmorin@chromium.org,alessiob@chromium.org

Change-Id: I00b1df98e043d2b845f3cee2a88e3307c7151939
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: webrtc:9577
Reviewed-on: https://chromium-review.googlesource.com/c/1459543
Auto-Submit: Ale Bzk <alessiob@chromium.org>
Commit-Queue: Mirko Bonadei <mbonadei@chromium.org>
Reviewed-by: Mirko Bonadei <mbonadei@chromium.org>
Cr-Commit-Position: refs/heads/master@{#630282}

BUILD.gn

@@ -775,13 +775,6 @@ group("gn_all") {
       "//tools/accessibility/inspect:ax_dump_tree",
     ]
   }
-
-  # PFFFT.
-  deps += [
-    "//third_party/pffft:fuzzers",
-    "//third_party/pffft:pffft_benchmark",
-    "//third_party/pffft:pffft_unittest",
-  ]
 }
 
 if ((is_linux || is_win) && enable_remoting && !use_ozone) {

third_party/pffft/README.chromium

@@ -13,7 +13,3 @@ Description:
 PFFFT does 1D Fast Fourier Transforms, of single precision real and complex vectors. It tries do it fast, it tries to be correct, and it tries to be small. Computations do take advantage of SSE1 instructions on x86 cpus, Altivec on powerpc cpus, and NEON on ARM cpus.
 
 Local Modifications:
- * 01-add_m_pi.diff: define M_PI if not defined
- * 02-rmv_printf.diff: remove printf and stop including stdio.h
- * 03-decl_validate_simd.diff: declare validate_pffft_simd() in pffft.h
- * 04-add_m_ln2.diff: define M_LN2 if not defined