sysutils/xen-tools: Update to 4.5.1 and apply XSA-139/XSA-140 patches

• Update to 4.5.1
• Remove XSA-117 to XSA-136 and elf_parse_bsdsyms patches now part of 4.5.1
• Leave XSA-135 QEMU traditional patches due an oversight in 4.5.1
• Apply patches for XSA-139/XSA-140
• Set USE_LDCONFIG, sort USES, use ${PATCH}, and reorder Makefile (portlint)

PR: 201931
Security: CVE-2015-5166
Security: ee99899d-4347-11e5-93ad-002590263bf5
Security: CVE-2015-5165
Security: f06f20dc-4347-11e5-93ad-002590263bf5
Approved by: bapt (maintainer), feld (mentor)
MFH: 2015Q3