Restrict the pattern in gdb.base/jit.exp

Restrict the pattern in gdb.base/jit.exp

I see the following fail in some thumb multi-lib in arm-none-linux-gnueabi,

info function jit_function^M
All functions matching regular expression "jit_function":^M
^M
Non-debugging symbols:^M
0x00000790  __real_jit_function_XXXX^M
0x0000079c  __jit_function_XXXX_from_arm^M
0x0000079c  jit_function_0000^M
0x00000790  __real_jit_function_XXXX^M
0x0000079c  __jit_function_XXXX_from_arm^M
0x0000079c  jit_function_0001^M
(gdb) FAIL: gdb.base/jit.exp: one_jit_test-2: info function jit_function

the test expects to see only jit_function_0000 and jit_function_0001

one_jit_test 2 "${hex}  jit_function_0000\[\r\n\]+${hex}  jit_function_0001"

Symbols with the prefix "__real_" or suffix "_from_arm" is generated
by gcc/ld for arm/thumb interworking.

This patch is to restrict the pattern from "jit_function" to
"^jit_function", the output becomes expected.

gdb/testsuite:

2014-06-06  Yao Qi  <yao@codesourcery.com>

	* gdb.base/jit.exp (one_jit_test): Restrict the pattern
	from "jit_function" to "^jit_function".