Move the ILP32 mmap() hackery into legacy_32_bit_support.cpp.
Every time I look at mmap.cpp, I fail to realize it's only built for ILP32.
Also improve some of the commentary in SYSCALLS.TXT and legacy_32_bit_support.cpp.
Change-Id: Ieedfe800b437e30c060c3e8663b6d96d517dbf6f
diff --git a/libc/SYSCALLS.TXT b/libc/SYSCALLS.TXT
index 0db5d79..ce14e49 100644
--- a/libc/SYSCALLS.TXT
+++ b/libc/SYSCALLS.TXT
@@ -174,20 +174,21 @@
off_t lseek(int, off_t, int) lp32
int __llseek:_llseek(int, unsigned long, unsigned long, off64_t*, int) lp32
off_t lseek|lseek64(int, off_t, int) lp64
-int ftruncate64(int, off64_t) lp32
-int ftruncate|ftruncate64(int, off_t) lp64
ssize_t sendfile(int out_fd, int in_fd, off_t* offset, size_t count) lp32
ssize_t sendfile64(int out_fd, int in_fd, off64_t* offset, size_t count) lp32
ssize_t sendfile|sendfile64(int out_fd, int in_fd, off_t* offset, size_t count) lp64
int truncate(const char*, off_t) lp32
int truncate64(const char*, off64_t) lp32
int truncate|truncate64(const char*, off_t) lp64
-# (mmap only gets two lines because we only used the 64-bit variant on 32-bit systems.)
-void* __mmap2:mmap2(void*, size_t, int, int, int, long) lp32
-void* mmap|mmap64(void*, size_t, int, int, int, off_t) lp64
# (fallocate only gets two lines because there is no 32-bit variant.)
int fallocate64:fallocate(int, int, off64_t, off64_t) lp32
int fallocate|fallocate64(int, int, off_t, off_t) lp64
+# (ftruncate only gets two lines because 32-bit bionic only uses the 64-bit call.)
+int ftruncate64(int, off64_t) lp32
+int ftruncate|ftruncate64(int, off_t) lp64
+# (mmap only gets two lines because 32-bit bionic only uses the 64-bit call.)
+void* __mmap2:mmap2(void*, size_t, int, int, int, long) lp32
+void* mmap|mmap64(void*, size_t, int, int, int, off_t) lp64
# posix_fadvise64 is awkward: arm has shuffled arguments,
# the POSIX functions don't set errno, and no architecture has posix_fadvise.