Add __aeabi_idiv to the dummy reference list.

If the platform code is compiled with -mcpu=cortex-a15, then without this
change prebuilt libraries built against -march=armv7 cannot resolve the
dependency on __aeabi_idiv (provided by libgcc.a).

Bug: 7961327

Change-Id: I0a05ce9c44e44d39b8ce1f0e319e2d37a010f3c7
diff --git a/libc/arch-arm/bionic/libgcc_compat.c b/libc/arch-arm/bionic/libgcc_compat.c
index a5cb219..e4473f3 100644
--- a/libc/arch-arm/bionic/libgcc_compat.c
+++ b/libc/arch-arm/bionic/libgcc_compat.c
@@ -110,6 +110,7 @@
     XX(__aeabi_fsub)         \
     XX(__aeabi_i2d)          \
     XX(__aeabi_i2f)          \
+    XX(__aeabi_idiv)         \
     XX(__aeabi_l2d)          \
     XX(__aeabi_l2f)          \
     XX(__aeabi_lmul)         \