[S] Change in coreboot[main]: lib/string: change return types to match C standard

[Elyes Haouas (Code Review)]

Elyes Haouas has submitted this change. ( https://review.coreboot.org/c/coreboot/+/83223?usp=email )

Change subject: lib/string: change return types to match C standard
......................................................................

lib/string: change return types to match C standard

The return type of strspn and strcspn is supposed to be a size_t and not
a signed integer.

TEST=Now the openSIL code can be built with the coreboot headers without
needing to add '-Wno-builtin-declaration-mismatch' or
'-Wno-incompatible-library-redeclaration' to the cflags. Before the
build would error out with various 'mismatch in return type of built-in
function' errors.

Signed-off-by: Felix Held 
Change-Id: I0ff612e2eee4f556f5c572b02cbc600ca411ae20
Reviewed-on: https://review.coreboot.org/c/coreboot/+/83223
Reviewed-by: Marshall Dawson 
Tested-by: build bot (Jenkins) 
Reviewed-by: Elyes Haouas 
Reviewed-by: Varshit Pandya 
Reviewed-by: Matt DeVillier 
---
M src/include/string.h
M src/lib/string.c
2 files changed, 6 insertions(+), 6 deletions(-)

Approvals:
  Elyes Haouas: Looks good to me, approved
  Matt DeVillier: Looks good to me, approved
  build bot (Jenkins): Verified
  Varshit Pandya: Looks good to me, but someone else must approve
  Marshall Dawson: Looks good to me, approved

diff --git a/src/include/string.h b/src/include/string.h
index dc301ea..30d014a 100644
--- a/src/include/string.h
+++ b/src/include/string.h
@@ -20,8 +20,8 @@
 char *strcpy(char *dst, const char *src);
 int strcmp(const char *s1, const char *s2);
 int strncmp(const char *s1, const char *s2, size_t maxlen);
-int strspn(const char *str, const char *spn);
-int strcspn(const char *str, const char *spn);
+size_t strspn(const char *str, const char *spn);
+size_t strcspn(const char *str, const char *spn);
 char *strstr(const char *haystack, const char *needle);
 char *strtok_r(char *str, const char *delim, char **ptr);
 char *strtok(char *str, const char *delim);
diff --git a/src/lib/string.c b/src/lib/string.c
index 7553295..b1996ff 100644
--- a/src/lib/string.c
+++ b/src/lib/string.c
@@ -125,9 +125,9 @@
    return 0;
 }

-int strspn(const char *str, const char *spn)
+size_t strspn(const char *str, const char *spn)
 {
-	int ret = 0;
+	size_t ret = 0;

while (*str != 0) {
    	const char *p;
@@ -140,9 +140,9 @@
    return ret;
 }

-int strcspn(const char *str, const char *spn)
+size_t strcspn(const char *str, const char *spn)
 {
-	int ret = 0;
+	size_t ret = 0;

while (*str != 0) {
    	const char *p;