Modify signed constant FNV1_BASE_32 to unsigned to suppress compiler
warning: subversion/libsvn_subr/file.c: In function
'calc_hash':subversion/libsvn_subr/file.c:149:3: warning: this decimal
constant is unsigned only in ISO C90 [enabled by default]

* subversion/libsvn_subr/file.c 
  (FNV1_BASE_32): Modify signed constant FNV1_BASE_32 to unsigned
    constant.

Approved by: philip

git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1526594 13f79535-47bb-0310-9956-ffa450edef68