I haven't looked exactly why this happens but here is the problem:

$ cat <<EOF >test.c
#include <stdio.h>
void foo() {
  printf("foo\n");
}
EOF
$ gcc -o test.so -shared test.c -mthumb -fPIC -Os -march=armv7-a
$ objdump -d test.so
test.so:     file format elf32-littlearm


Disassembly of section .plt:

000001d0 <.plt>:
 1d0:	e52de004 	.word	0xe52de004
 1d4:	e59fe004 	.word	0xe59fe004
 1d8:	e08fe00e 	.word	0xe08fe00e
 1dc:	e5bef008 	.word	0xe5bef008
 1e0:	000010c8 	.word	0x000010c8
 1e4:	e28fc600 	.word	0xe28fc600
 1e8:	e28cca01 	.word	0xe28cca01
 1ec:	e5bcf0c8 	.word	0xe5bcf0c8

Disassembly of section .text:

000001f0 <foo>:
 1f0:	4801      	ldr	r0, [pc, #4]	; (1f8 <foo+0x8>)
 1f2:	4478      	add	r0, pc
 1f4:	f000 b802 	b.w	1fc <foo+0xc>
 1f8:	00000016 	.word	0x00000016
 1fc:	46c04778 	.word	0x46c04778
 200:	e59fc000 	.word	0xe59fc000
 204:	e08cf00f 	.word	0xe08cf00f
 208:	ffffffd8 	.word	0xffffffd8

With GNU ld:
$ gcc -o test.so -shared test.c -mthumb -fPIC -Os -march=armv7-a
$ objdump -d test.so
test.so:     file format elf32-littlearm


Disassembly of section .plt:

00000260 <.plt>:
 260:	e52de004 	push	{lr}		; (str lr, [sp, #-4]!)
 264:	e59fe004 	ldr	lr, [pc, #4]	; 270 <foo-0x14>
 268:	e08fe00e 	add	lr, pc, lr
 26c:	e5bef008 	ldr	pc, [lr, #8]!
 270:	000080b4 	.word	0x000080b4
 274:	4778      	bx	pc
 276:	46c0      	nop			; (mov r8, r8)
 278:	e28fc600 	add	ip, pc, #0
 27c:	e28cca08 	add	ip, ip, #32768	; 0x8000
 280:	e5bcf0b0 	ldr	pc, [ip, #176]!	; 0xb0

Disassembly of section .text:

00000284 <foo>:
 284:	4801      	ldr	r0, [pc, #4]	; (28c <foo+0x8>)
 286:	4478      	add	r0, pc
 288:	f7ff bff4 	b.w	274 <foo-0x10>
 28c:	00000006 	.word	0x00000006