ROMIO: add strtolower function

a lot more straightforward to just lowercase the string than to try to
check all the different case possibilities of strings.  Useful in hint
processing too, but not used there yet.

Author: roblatham00

src/mpi/romio/adio/common/strfns.c

@@ -102,3 +102,18 @@ char *ADIOI_Strdup(const char *str)
     }
     return save_p;
 }
+
+/*
+ * Convert string to lowercase
+ * Converts inplace, returns pointer to str
+ */
+char *ADIOI_Strlower(char *str)
+{
+    if (!str)
+        return str;
+    while (*str) {
+        *str = tolower(*str);
+        str++;
+    }
+    return str;
+}

src/mpi/romio/adio/include/adioi.h

@@ -849,6 +849,7 @@ int ADIOI_Set_lock64(FDTYPE fd_sys, int cmd, int type, ADIO_Offset offset, int w
 
 int ADIOI_Strncpy(char *outstr, const char *instr, size_t maxlen);
 char *ADIOI_Strdup(const char *);
+char *ADIOI_Strlower(char *str);
 
 /* the current MPI standard is not const-correct, and modern compilers warn
  * about the following sort of code: