mips: remove --mips64r6 configure option

Having a configure option with the same name as a MIPS ISA is confusing,
so better to remove it. This option was being used to add some
optimizations to a specific core (i6400). We will add the optimizations
just when the i6400 core has been detected, in a later patch.
Signed-off-by: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

Changelog

@@ -42,6 +42,7 @@ version <next>:
 - mipsdspr1 option has been renamed to mipsdsp
 - aemphasis filter
 - mips32r5 option has been removed
+- mips64r6 option has been removed
 - DXVA2-accelerated VP9 decoding
 
 

configure

@@ -384,7 +384,6 @@ Optimization options (experts only):
   --disable-neon           disable NEON optimizations
   --disable-inline-asm     disable use of inline assembly
   --disable-yasm           disable use of nasm/yasm assembly
-  --disable-mips64r6       disable MIPS64R6 optimizations
   --disable-mipsdsp        disable MIPS DSP ASE R1 optimizations
   --disable-mipsdspr2      disable MIPS DSP ASE R2 optimizations
   --disable-msa            disable MSA optimizations
@@ -5006,14 +5005,8 @@ elif enabled mips; then
     elif enabled mipsdsp || enabled mipsdspr2; then
         add_cflags "-mips32r2 -mfp32"
         add_asflags "-mips32r2 -mfp32"
-    elif enabled mips64r6; then
-        check_cflags "-mfp64"
-        check_ldflags "-mfp64"
     fi
 
-    enabled mips64r6  && check_cflags "-mips64r6 -msched-weight -mload-store-pairs -funroll-loops" &&
-     check_ldflags "-mips64r6" &&
-     check_inline_asm mips64r6  '"aui $t0, $t1, 1"'
     enabled mipsdsp && add_cflags "-mdsp" && add_asflags "-mdsp" &&
      check_inline_asm mipsdsp '"addu.qb $t0, $t1, $t2"'
     enabled mipsdspr2 && add_cflags "-mdspr2" && add_asflags "-mdspr2" &&
@@ -5023,7 +5016,6 @@ elif enabled mips; then
     enabled msa       && check_cflags "-mmsa" && check_ldflags "-mmsa" &&
      check_inline_asm msa       '"addvi.b $w0, $w1, 1"'
 
-    enabled mips64r6 && add_asflags "-mips64r6 -mfp64"
     enabled msa && add_asflags "-mmsa"
 
 elif enabled parisc; then
@@ -6096,7 +6088,6 @@ if enabled arm; then
 fi
 if enabled mips; then
     echo "MIPS FPU enabled          ${mipsfpu-no}"
-    echo "MIPS64R6 enabled          ${mips64r6-no}"
     echo "MIPS DSP R1 enabled       ${mipsdsp-no}"
     echo "MIPS DSP R2 enabled       ${mipsdspr2-no}"
     echo "MIPS MSA enabled          ${msa-no}"