[arm] Don't pass -mfpu=auto through to the assembler.

The assembler doesn't understand -mfpu=auto.  The easiest way to handle this
is to surpress this value from being passed through, while still passing
through legacy values.

	* config/arm/elf.h (ASM_SPEC): Only pass -mfpu through to the
	assembler when it is not -mfpu=auto.

From-SVN: r249281

gcc/ChangeLog

+2017-06-16  Richard Earnshaw  <rearnsha@arm.com>
+
+	* config/arm/elf.h (ASM_SPEC): Only pass -mfpu through to the
+	assembler when it is not -mfpu=auto.
+
 2017-06-16  Richard Earnshaw  <rearnsha@arm.com>
 	* config/arm/arm.h (BIG_LITTLE_SPEC): Delete macro.

gcc/config/arm/elf.h

@@ -64,7 +64,7 @@
 %{mapcs-*:-mapcs-%*} \
 %(subtarget_asm_float_spec) \
 %{mthumb-interwork:-mthumb-interwork} \
-%{mfloat-abi=*} %{mfpu=*} \
+%{mfloat-abi=*} %{!mfpu=auto: %{mfpu=*}} \
 %(subtarget_extra_asm_spec)"
 #endif