Change {read,write}FileAt() SAL_INFO calls to use a separate log area

Keep sal.file for the SAL_INFO logging of file system calls (open,
close, rename, etc), and use sal.fileio for the (very verbose) file
I/O.

Change-Id: I0e166d83e20921696a8a0880f9fcbbdec55053dd

include/sal/log-areas.dox

@@ -22,7 +22,8 @@ certain functionality.
 
 @li @c sal.bootstrap - SAL bootstrap
 @li @c sal.debug - SAL debugging functionality
-@li @c sal.file
+@li @c sal.file - file system operations
+@li @c sal.fileio - file I/O
 @li @c sal.osl - SAL OSL library
 @li @c sal.osl.condition
 @li @c sal.osl.mutex

sal/osl/unx/file.cxx

@@ -425,7 +425,7 @@ oslFileError FileHandle_Impl::readFileAt(
         }
 
         size_t const bytes = std::min(m_buflen - bufpos, nBytesRequested);
-        SAL_INFO("sal.file", "FileHandle_Impl::readFileAt(" << m_fd << ", " << nOffset << ", " << bytes << ")");
+        SAL_INFO("sal.fileio", "FileHandle_Impl::readFileAt(" << m_fd << ", " << nOffset << ", " << bytes << ")");
 
         memcpy(&(buffer[*pBytesRead]), &(m_buffer[bufpos]), bytes);
         nBytesRequested -= bytes;
@@ -500,7 +500,7 @@ oslFileError FileHandle_Impl::writeFileAt(
         }
 
         size_t const bytes = std::min(m_bufsiz - bufpos, nBytesToWrite);
-        SAL_INFO("sal.file", "FileHandle_Impl::writeFileAt(" << m_fd << ", " << nOffset << ", " << bytes << ")");
+        SAL_INFO("sal.fileio", "FileHandle_Impl::writeFileAt(" << m_fd << ", " << nOffset << ", " << bytes << ")");
 
         memcpy(&(m_buffer[bufpos]), &(buffer[*pBytesWritten]), bytes);
         nBytesToWrite -= bytes;