Rollup merge of rust-lang#31800 - alexcrichton:armv6-plz, r=brson

Right now the compiler's we're using actually default to armv7/thumb2 I believe,
so this should help push them back to what the arm-unknown-linux-* targets are
for. This at least matches that clang does for the `arm-unknown-linux-gnueabihf`
target which is to map it to an armv6 architecture.

Closes rust-lang#31787

Author: Manishearth

mk/cfg/arm-unknown-linux-gnueabi.mk

@@ -8,8 +8,8 @@ CFG_LIB_NAME_arm-unknown-linux-gnueabi=lib$(1).so
 CFG_STATIC_LIB_NAME_arm-unknown-linux-gnueabi=lib$(1).a
 CFG_LIB_GLOB_arm-unknown-linux-gnueabi=lib$(1)-*.so
 CFG_LIB_DSYM_GLOB_arm-unknown-linux-gnueabi=lib$(1)-*.dylib.dSYM
-CFG_JEMALLOC_CFLAGS_arm-unknown-linux-gnueabi := -D__arm__ -mfloat-abi=soft $(CFLAGS)
-CFG_GCCISH_CFLAGS_arm-unknown-linux-gnueabi := -Wall -g -fPIC -D__arm__ -mfloat-abi=soft $(CFLAGS)
+CFG_JEMALLOC_CFLAGS_arm-unknown-linux-gnueabi := -D__arm__ -mfloat-abi=soft $(CFLAGS) -march=armv6 -marm
+CFG_GCCISH_CFLAGS_arm-unknown-linux-gnueabi := -Wall -g -fPIC -D__arm__ -mfloat-abi=soft $(CFLAGS) -march=armv6 -marm
 CFG_GCCISH_CXXFLAGS_arm-unknown-linux-gnueabi := -fno-rtti $(CXXFLAGS)
 CFG_GCCISH_LINK_FLAGS_arm-unknown-linux-gnueabi := -shared -fPIC -g
 CFG_GCCISH_DEF_FLAG_arm-unknown-linux-gnueabi := -Wl,--export-dynamic,--dynamic-list=

mk/cfg/arm-unknown-linux-gnueabihf.mk

@@ -8,8 +8,8 @@ CFG_LIB_NAME_arm-unknown-linux-gnueabihf=lib$(1).so
 CFG_STATIC_LIB_NAME_arm-unknown-linux-gnueabihf=lib$(1).a
 CFG_LIB_GLOB_arm-unknown-linux-gnueabihf=lib$(1)-*.so
 CFG_LIB_DSYM_GLOB_arm-unknown-linux-gnueabihf=lib$(1)-*.dylib.dSYM
-CFG_JEMALLOC_CFLAGS_arm-unknown-linux-gnueabihf := -D__arm__ $(CFLAGS)
-CFG_GCCISH_CFLAGS_arm-unknown-linux-gnueabihf := -Wall -g -fPIC -D__arm__ $(CFLAGS)
+CFG_JEMALLOC_CFLAGS_arm-unknown-linux-gnueabihf := -D__arm__ $(CFLAGS) -march=armv6 -marm
+CFG_GCCISH_CFLAGS_arm-unknown-linux-gnueabihf := -Wall -g -fPIC -D__arm__ $(CFLAGS) -march=armv6 -marm
 CFG_GCCISH_CXXFLAGS_arm-unknown-linux-gnueabihf := -fno-rtti $(CXXFLAGS)
 CFG_GCCISH_LINK_FLAGS_arm-unknown-linux-gnueabihf := -shared -fPIC -g
 CFG_GCCISH_DEF_FLAG_arm-unknown-linux-gnueabihf := -Wl,--export-dynamic,--dynamic-list=