Makefile: Improve auto-detection of ARM cross compiler

This patch moves the scan for an ARM gcc into a separate shell
script. To prevent against recursion issues, the new script adds
"-maxdepth 1" to the find invocation; and it now also correctly
handles directories in $PATH that contain spaces in their name.
Signed-off-by: Bernhard Nortmann <bernhard.nortmann@web.de>

Makefile

@@ -56,8 +56,8 @@ MKSUNXIBOOT ?= mksunxiboot
 PATH_DIRS := $(shell echo $$PATH | sed -e 's/:/ /g')
 # Try to guess a suitable default ARM cross toolchain
 CROSS_DEFAULT := arm-none-eabi-
-CROSS_COMPILE ?= $(or $(shell find $(PATH_DIRS) -executable -name 'arm*-gcc' -printf '%f\t' 2>/dev/null | cut -f 1 | sed -e 's/-gcc/-/'),$(CROSS_DEFAULT))
-CROSS_CC ?= $(CROSS_COMPILE)gcc
+CROSS_COMPILE ?= $(or $(shell ./find-arm-gcc.sh),$(CROSS_DEFAULT))
+CROSS_CC := $(CROSS_COMPILE)gcc
 
 DESTDIR ?=
 PREFIX  ?= /usr/local

find-arm-gcc.sh

+#
+# Try to locate suitable ARM cross compilers available via $PATH
+# If any are found, this function will output them as a TAB-delimited list
+#
+scan_path () {
+IFS=":"
+for path in $PATH; do
+	find "$path" -maxdepth 1 -executable -name 'arm*-gcc' -printf '%f\t' 2>/dev/null
+done
+}
+
+# Use only the first field from result, and convert it to a toolchain prefix
+scan_path | cut -f 1 | sed -e 's/-gcc/-/'

thunks/Makefile

@@ -17,8 +17,7 @@ all: $(SPL_THUNK) $(THUNKS)
 FORCE:
 
 # If not specified explicitly: try to guess a suitable ARM toolchain prefix
-PATH_DIRS := $(shell echo $$PATH | sed -e 's/:/ /g')
-CROSS_COMPILE ?= $(shell find $(PATH_DIRS) -executable -name 'arm*-gcc' -printf '%f\t' | cut -f 1 | sed -e 's/-gcc/-/')
+CROSS_COMPILE ?= $(shell ../find-arm-gcc.sh)
 
 AS := $(CROSS_COMPILE)as
 OBJDUMP := $(CROSS_COMPILE)objdump