Add three new blind options to set use of Thumb mode:
- COMPILE_IN_THUMB_MODE
  - if set, CFLAGS will contain -mthumb
  - if unset, the compiler's default is used
- HAS_THUMB
  - CPUS with Thumb instruction set can select this
  - use of BX depends on this
- FORCE_THUMB
  - CPUs that are Thumb-only must select this
  - this selects: HAS_THUMB, COMPILE_IN_THUMB_MODE and USE_BX

Also, remove leading space in Rules.mak.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>
Cc: Khem Raj <raj.khem@gmail.com>
Cc: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>
Cc: Carmelo AMOROSO <carmelo.amoroso@st.com>
---
 Rules.mak                |    7 ++++---
 extra/Configs/Config.arm |   31 ++++++++++++++++++++++++++++---
 2 files changed, 32 insertions(+), 6 deletions(-)

--- a/Rules.mak
+++ b/Rules.mak
@@ -351,9 +351,10 @@ ifeq ($(TARGET_ARCH),arm)
 	CPU_CFLAGS-$(CONFIG_ARM_SA1100)+=-mtune=strongarm1100 -march=armv4
 	CPU_CFLAGS-$(CONFIG_ARM_XSCALE)+=$(call check_gcc,-mtune=xscale,-mtune=strongarm110)
 	CPU_CFLAGS-$(CONFIG_ARM_XSCALE)+=-march=armv5te -Wa,-mcpu=xscale
- 	CPU_CFLAGS-$(CONFIG_ARM_IWMMXT)+=-march=iwmmxt -Wa,-mcpu=iwmmxt -mabi=iwmmxt
- 	CPU_CFLAGS-$(CONFIG_ARM_CORTEX_M3)+=-mcpu=cortex-m3 -mthumb
- 	CPU_CFLAGS-$(CONFIG_ARM_CORTEX_M1)+=-mcpu=cortex-m1 -mthumb
+	CPU_CFLAGS-$(CONFIG_ARM_IWMMXT)+=-march=iwmmxt -Wa,-mcpu=iwmmxt -mabi=iwmmxt
+	CPU_CFLAGS-$(CONFIG_ARM_CORTEX_M3)+=-mcpu=cortex-m3
+	CPU_CFLAGS-$(CONFIG_ARM_CORTEX_M1)+=-mcpu=cortex-m1
+	CPU_CFLAGS-$(COMPILE_IN_THUMB_MODE)+=-mthumb
 endif
 
 ifeq ($(TARGET_ARCH),mips)
--- a/extra/Configs/Config.arm
+++ b/extra/Configs/Config.arm
@@ -64,70 +64,95 @@ config CONFIG_ARM710
 config CONFIG_ARM7TDMI
 	bool "Arm 7TDMI"
 	select ARCH_HAS_NO_MMU
+	select HAS_THUMB
 
 config CONFIG_ARM720T
 	bool "Arm 720T"
 	select ARCH_HAS_MMU
+	select HAS_THUMB
 
 config CONFIG_ARM920T
 	bool "Arm 920T"
 	select ARCH_HAS_MMU
+	select HAS_THUMB
 
 config CONFIG_ARM922T
 	bool "Arm 922T"
 	select ARCH_HAS_MMU
+	select HAS_THUMB
 
 config CONFIG_ARM926T
 	bool "Arm 926T"
 	select ARCH_HAS_MMU
+	select HAS_THUMB
 
 config CONFIG_ARM10T
 	bool "Arm 10T"
 	select ARCH_HAS_MMU
+	select HAS_THUMB
 
 config CONFIG_ARM1136JF_S
 	bool "Arm 1136JF-S"
 	select ARCH_HAS_MMU
+	select HAS_THUMB
 
 config CONFIG_ARM1176JZ_S
 	bool "Arm 1176JZ-S"
 	select ARCH_HAS_MMU
+	select HAS_THUMB
 
 config CONFIG_ARM1176JZF_S
 	bool "Arm 1176JZF-S"
 	select ARCH_HAS_MMU
+	select HAS_THUMB
 
 config CONFIG_ARM_CORTEX_M3
 	bool "Arm Cortex-M3"
 	select ARCH_HAS_NO_MMU
-	select USE_BX
+	select FORCE_THUMB
 
 config CONFIG_ARM_CORTEX_M1
 	bool "Arm Cortex-M1"
 	select ARCH_HAS_NO_MMU
-	select USE_BX
+	select FORCE_THUMB
 
 config CONFIG_ARM_SA110
 	bool "Intel StrongArm SA-110"
 	select ARCH_HAS_MMU
+	select HAS_THUMB
 
 config CONFIG_ARM_SA1100
 	bool "Intel StrongArm SA-1100"
 	select ARCH_HAS_MMU
+	select HAS_THUMB
 
 config CONFIG_ARM_XSCALE
 	bool "Intel Xscale"
 	select ARCH_HAS_MMU
+	select HAS_THUMB
 
 config CONFIG_ARM_IWMMXT
 	bool "Intel Xscale With WMMX PXA27x"
 	select ARCH_HAS_MMU
+	select HAS_THUMB
 
 endchoice
 
+config HAS_THUMB
+	bool
+
+config FORCE_THUMB
+	bool
+	select HAS_THUMB
+	select COMPILE_IN_THUMB_MODE
+	select USE_BX
+
+config COMPILE_IN_THUMB_MODE
+	bool
+
 config USE_BX
 	bool "Use BX in function return"
 	default y
-	depends on !CONFIG_GENERIC_ARM && !CONFIG_ARM610 && !CONFIG_ARM710
+	depends on HAS_THUMB
 	help
 	  Use BX instruction for THUMB aware architectures.