Change in flashrom[master]: Revert "Makefile: Explicitly set '-std=c99'"

[Angel Pons (Code Review)]

Attention is currently required from: Sam McNally, Nico Huber, Stefan Reinauer, Edward O'Callaghan, Anastasia Klimchuk, Nikolai Artemiev.
Hello Sam McNally, build bot (Jenkins), Nico Huber, Stefan Reinauer, Edward O'Callaghan, Anastasia Klimchuk, Nikolai Artemiev,

I'd like you to do a code review. Please visit

https://review.coreboot.org/c/flashrom/+/52425

to review the following change.

Change subject: Revert "Makefile: Explicitly set '-std=c99'"
......................................................................

Revert "Makefile: Explicitly set '-std=c99'"

This reverts commit 5e5c3f15efe262ff23642dd543faf6a9dbb3bbdb.

Reason for revert: Breaks building on PowerPC, NetBSD, DJGPP, and it is
possible that SPARC fails to build as well.

Change-Id: I57b5125207de3fd156dface67cba605da893d6aa
Signed-off-by: Angel Pons 
---
M Makefile
M dmi.c
2 files changed, 1 insertion(+), 3 deletions(-)

git pull ssh://review.coreboot.org:29418/flashrom refs/changes/25/52425/1

diff --git a/Makefile b/Makefile
index 6d37d55..09b2154 100644
--- a/Makefile
+++ b/Makefile
@@ -30,7 +30,7 @@
 DIFF    = diff
 PREFIX  ?= /usr/local
 MANDIR  ?= $(PREFIX)/share/man
-CFLAGS  ?= -std=c99 -D_DEFAULT_SOURCE -D_POSIX_C_SOURCE=200809L -D_BSD_SOURCE -Os -Wall -Wextra -Wno-unused-parameter -Wshadow -Wmissing-prototypes -Wwrite-strings
+CFLAGS  ?= -Os -Wall -Wextra -Wno-unused-parameter -Wshadow -Wmissing-prototypes -Wwrite-strings
 EXPORTDIR ?= .
 RANLIB  ?= ranlib
 PKG_CONFIG ?= pkg-config
diff --git a/dmi.c b/dmi.c
index 3b717cd..c44221c 100644
--- a/dmi.c
+++ b/dmi.c
@@ -19,9 +19,7 @@

/* strnlen is in POSIX but was a GNU extension up to glibc 2.10 */
 #if (__GLIBC__ == 2 && __GLIBC_MINOR__ < 10) || __GLIBC__ < 2
-#ifndef _GNU_SOURCE
 #define _GNU_SOURCE
-#endif /* !GNU_SOURCE */
 #else
 #define _POSIX_C_SOURCE 200809L
 #endif