Fix usage of _te32/_te64/_te16 for Elf classes

How did it ever work?  UPX_RSIZE_MAX_MEM of 768MiB, Elf32_Off of only
32-bits, and preponderance of little-endian and small positive integers
hides many mis-uses of _te64/_te32.
ELF does not help: e_phnum, e_shnum, Elf32_Section, Elf64_Section are all
16-bit, but sh_info and sh_link are 32-bit.
Templatizing p_elf.h (following the example of p_mach.h) failed
because of complexity.  (Plus too many special cases of ELF where 32-bit
and 64-bit are not parallel.)
	modified:   p_lx_elf.cpp
	modified:   p_lx_sh.cpp
	modified:   p_mach.cpp

src/p_lx_sh.cpp

@@ -91,7 +91,7 @@ PackLinuxI386sh::buildLoader(Filter const *ft)
     // filter
     optimizeFilter(&fold_ft, buf, sz_fold);
     unsigned fold_hdrlen = sizeof(l_info) + sizeof(Elf32_Ehdr) +
-        sizeof(Elf32_Phdr) * get_te32(&((Elf32_Ehdr const *)(void *)buf)->e_phnum);
+        sizeof(Elf32_Phdr) * get_te16(&((Elf32_Ehdr const *)(void *)buf)->e_phnum);
     if (0 == get_le32(buf + fold_hdrlen)) {
         // inconsistent SIZEOF_HEADERS in *.lds (ld, binutils)
         fold_hdrlen = umax(0x80, fold_hdrlen);