Makefile: Fix building on AArch64 NixOS

The parsing of the output of archtest.c produced an unexpected
value on AArch64 NixOS. For example, the make variable ARCH was set to:

```
bit outside of fd_set selected
arm
```

This made the arch and OS checks fail.

This commit simplifies the parsing, making it more robust.

The C files archtest.c, endiantest.c and os.h used to set the
TARGET_OS, ARCH and ENDIAN variables, respectively, output
the result of the test as the final line, so just extracting
the final line and removing double quoting is enough.

This commit also fixes a bug with debug_shell lacking escaping
single quotes, which prevented using the single quote in the
debug_shell calls. It used to work by accident before this fix;
the line in the call happened to contain a balanced pair of double
quotes and lacked other characters that needed escaping, which
didn't break the debug_shell, but this was accidental and very
brittle.

Signed-off-by: Pyry Kontio <pyry.kontio@drasa.eu>
Change-Id: Iaa4477a71e758cf9ecad2c22f3b77bc6508a3510
Reviewed-on: https://review.coreboot.org/c/flashrom/+/43140
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/67902
Reviewed-by: Thomas Heijligen <src@posteo.de>
---
M Makefile
1 file changed, 50 insertions(+), 6 deletions(-)

diff --git a/Makefile b/Makefile
index 7242b09..52a2f95 100644
--- a/Makefile
+++ b/Makefile
@@ -83,7 +83,8 @@
 
 # Provide an easy way to execute a command, print its output to stdout and capture any error message on stderr
 # in the build details file together with the original stdout output.
-debug_shell = $(shell export LC_ALL=C ; { echo 'exec: export LC_ALL=C ; { $(1) ; }' >&2;  { $(1) ; } | tee -a $(BUILD_DETAILS_FILE) ; echo >&2 ; } 2>>$(BUILD_DETAILS_FILE))
+debug_shell = $(shell export LC_ALL=C ; { echo 'exec: export LC_ALL=C ; { $(subst ','\'',$(1)) ; }' >&2; \
+    { $(1) ; } | tee -a $(BUILD_DETAILS_FILE) ; echo >&2 ; } 2>>$(BUILD_DETAILS_FILE))
 
 ###############################################################################
 # General OS-specific settings.
@@ -106,7 +107,8 @@
 # IMPORTANT: The following line must be placed before TARGET_OS is ever used
 # (of course), but should come after any lines setting CC because the line
 # below uses CC itself.
-override TARGET_OS := $(strip $(call debug_shell,$(CC) $(CPPFLAGS) -E os.h 2>/dev/null | grep -v '^\#' | grep '"' | cut -f 2 -d'"'))
+override TARGET_OS := $(strip $(call debug_shell,$(CC) $(CPPFLAGS) -E os.h 2>/dev/null \
+    | tail -1 | cut -f 2 -d'"'))
 
 ifeq ($(TARGET_OS), Darwin)
 override CPPFLAGS += -I/opt/local/include -I/usr/local/include
@@ -421,8 +423,10 @@
 # IMPORTANT: The following line must be placed before ARCH is ever used
 # (of course), but should come after any lines setting CC because the line
 # below uses CC itself.
-override ARCH := $(strip $(call debug_shell,$(CC) $(CPPFLAGS) -E archtest.c 2>/dev/null | grep -v '^\#' | grep '"' | cut -f 2 -d'"'))
-override ENDIAN := $(strip $(call debug_shell,$(CC) $(CPPFLAGS) -E endiantest.c 2>/dev/null | grep -v '^\#'))
+override ARCH := $(strip $(call debug_shell,$(CC) $(CPPFLAGS) -E archtest.c 2>/dev/null \
+    | tail -1 | cut -f 2 -d'"'))
+override ENDIAN := $(strip $(call debug_shell,$(CC) $(CPPFLAGS) -E endiantest.c 2>/dev/null \
+    | tail -1))
 
 # Disable the internal programmer on unsupported architectures (everything but x86 and mipsel)
 ifneq ($(ARCH)-little, $(filter $(ARCH),x86 mips)-$(ENDIAN))
@@ -1182,12 +1186,12 @@
 	@printf "Target arch is "
 	@# FreeBSD wc will output extraneous whitespace.
 	@echo $(ARCH)|wc -w|grep -q '^[[:blank:]]*1[[:blank:]]*$$' ||	\
-		( echo "unknown. Aborting."; exit 1)
+		( echo "unknown (\"$(ARCH)\"). Aborting."; exit 1)
 	@printf "%s\n" '$(ARCH)'
 	@printf "Target OS is "
 	@# FreeBSD wc will output extraneous whitespace.
 	@echo $(TARGET_OS)|wc -w|grep -q '^[[:blank:]]*1[[:blank:]]*$$' ||	\
-		( echo "unknown. Aborting."; exit 1)
+		( echo "unknown (\"$(TARGET_OS)\"). Aborting."; exit 1)
 	@printf "%s\n" '$(TARGET_OS)'
 ifeq ($(TARGET_OS), libpayload)
 	@$(CC) --version 2>&1 | grep -q coreboot || \

