Improve detection of memrchr, strlcat, and strlcpy.

This is continuation of commit f8d82a1010 addressing [perl #133760].
Linux systems using the musl C library have memmem, memrchr, strlcat, and
strlcpy, but the prototypes are only visible if _GNU_SOURCE is defined.
This patch makes Configure test both whether the prototype is visible
and whether the C symbol is visible.

Still to be done is automatically adding _GNU_SOURCE if the musl library
is being used -- probably in hints/linux.sh.

(cherry picked from commit ba73a4cb8f472480a2d630613d1e9e1172d518d3)

1 files changed, 57 insertions, 6 deletions

diff --git a/Configure b/Configure
index 0cb7179d55..f99377e9dd 100755
--- a/Configure
+++ b/Configure
@@ -16196,8 +16196,25 @@ case "$d_memmem_proto" in
 esac
 
 : see if memrchr exists
-set memrchr d_memrchr
-eval $inlibc
+: We need both a prototype in string.h and the symbol in libc.
+echo " "
+d_memrchr_proto=''
+xx1="#$d_gnulibc HAS_GNULIBC"
+xx2='#if defined(HAS_GNULIBC) && !defined(_GNU_SOURCE)'
+xx3='#   define _GNU_SOURCE'
+xx4='#endif'
+set d_memrchr_proto memrchr literal "$xx1" literal "$xx2" literal "$xx3" literal "$xx4" define string.h
+eval $hasproto
+case "$d_memrchr_proto" in
+    define) # see if memrchr exists
+	set memrchr d_memrchr
+	eval $inlibc
+	;;
+    *)  val=$undef
+	set d_memrchr
+	eval $setvar
+	;;
+esac
 
 : see if mkdir exists
 set mkdir d_mkdir
@@ -18806,12 +18823,46 @@ set strftime d_strftime
 eval $inlibc
 
 : see if strlcat exists
-set strlcat d_strlcat
-eval $inlibc
+: We need both a prototype in string.h and the symbol in libc.
+echo " "
+d_strlcat_proto=''
+xx1="#$d_gnulibc HAS_GNULIBC"
+xx2='#if defined(HAS_GNULIBC) && !defined(_GNU_SOURCE)'
+xx3='#   define _GNU_SOURCE'
+xx4='#endif'
+set d_strlcat_proto strlcat literal "$xx1" literal "$xx2" literal "$xx3" literal "$xx4" define string.h
+eval $hasproto
+case "$d_strlcat_proto" in
+    define) # see if strlcat exists
+	set strlcat d_strlcat
+	eval $inlibc
+	;;
+    *)  val=$undef
+	set d_strlcat
+	eval $setvar
+	;;
+esac
 
 : see if strlcpy exists
-set strlcpy d_strlcpy
-eval $inlibc
+: We need both a prototype in string.h and the symbol in libc.
+echo " "
+d_strlcpy_proto=''
+xx1="#$d_gnulibc HAS_GNULIBC"
+xx2='#if defined(HAS_GNULIBC) && !defined(_GNU_SOURCE)'
+xx3='#   define _GNU_SOURCE'
+xx4='#endif'
+set d_strlcpy_proto strlcpy literal "$xx1" literal "$xx2" literal "$xx3" literal "$xx4" define string.h
+eval $hasproto
+case "$d_strlcpy_proto" in
+    define) # see if strlcpy exists
+	set strlcpy d_strlcpy
+	eval $inlibc
+	;;
+    *)  val=$undef
+	set d_strlcpy
+	eval $setvar
+	;;
+esac
 
 : see if strnlen exists
 set strnlen d_strnlen