firefox-esr: backport kettenis's fft.asm fix from ffmpeg. Fixes an x-only

crash reported by ratchov.

www/firefox-esr/Makefile

@@ -7,6 +7,7 @@ MOZILLA_BRANCH =	release
 MOZILLA_PROJECT =	firefox-esr
 MOZILLA_CODENAME =	browser
 MOZILLA_DIST =		firefox
+REVISION =		0
 
 WRKDIST =	${WRKDIR}/${MOZILLA_DIST}-${MOZILLA_DIST_VERSION:C/esr//}
 HOMEPAGE =	https://www.mozilla.org/firefox/organizations/

www/firefox-esr/patches/patch-media_ffvpx_libavcodec_x86_fft_asm

@@ -0,0 +1,43 @@
+The x86 assembly FFT implementation uses dispatch tables in .text.  This is
+incompatible with x-only so move them into .data.rel.ro where we can have
+relocations.  But since they are in the RELRO segment they will be made
+read-only by ld.so after relocations have been processed.
+
+Index: media/ffvpx/libavcodec/x86/fft.asm
+--- media/ffvpx/libavcodec/x86/fft.asm.orig
++++ media/ffvpx/libavcodec/x86/fft.asm
+@@ -548,10 +548,6 @@ DEFINE_ARGS zc, w, n, o1, o3
+ %macro FFT_DISPATCH 2; clobbers 5 GPRs, 8 XMMs
+     lea r2, [dispatch_tab%1]
+     mov r2, [r2 + (%2q-2)*gprsize]
+-%ifdef PIC
+-    lea r3, [$$]
+-    add r2, r3
+-%endif
+     call r2
+ %endmacro ; FFT_DISPATCH
+ 
+@@ -731,12 +727,6 @@ DECL_PASS pass_interleave_3dnow, PASS_BIG 0
+ %define pass_interleave_3dnowext pass_interleave_3dnow
+ %endif
+ 
+-%ifdef PIC
+-%define SECTION_REL - $$
+-%else
+-%define SECTION_REL
+-%endif
+-
+ %macro DECL_FFT 1-2 ; nbits, suffix
+ %ifidn %0, 1
+ %xdefine fullsuffix SUFFIX
+@@ -773,8 +763,10 @@ fft %+ n %+ fullsuffix:
+ %endrep
+ %undef n
+ 
++[SECTION .data.rel.ro write]
+ align 8
+ dispatch_tab %+ fullsuffix: pointer list_of_fft
++__?SECT?__
+ %endmacro ; DECL_FFT
+ 
+ %if HAVE_AVX_EXTERNAL