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

cherry-picked from internal master.

Change-Id: I8fe59a98eb53d641518b882523c1d6a724fb7e55
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)         \