bpo-46498: Add Platform triplets for LoongArch64

signed-off-by: Zhang Na
co-authors: WANG Xuerui

Author: loongson-zn

Misc/NEWS.d/next/Build/2022-06-20-15-15-11.gh-issue-90656.kFBbKe.rst

@@ -0,0 +1 @@
+Add platform triplets for LoongArch64

configure

@@ -960,6 +960,20 @@ cat > conftest.c <<EOF
         hppa-linux-gnu
 # elif defined(__ia64__)
         ia64-linux-gnu
+# elif defined(__loongarch__)
+#  if defined(__loongarch_lp64)
+#   if defined(__loongarch_soft_float)
+        loongarch64-linux-gnusf
+#   elif defined(__loongarch_single_float)
+        loongarch64-linux-gnuf32
+#   elif defined(__loongarch_double_float)
+        loongarch64-linux-gnu
+#   else
+#    error unknown platform triplet
+#   endif
+#  else
+#   error unknown platform triplet
+#  endif
 # elif defined(__m68k__) && !defined(__mcoldfire__)
         m68k-linux-gnu
 # elif defined(__mips_hard_float) && defined(__mips_isa_rev) && (__mips_isa_rev >=6) && defined(_MIPSEL)